merge(third_party/git): Merge squashed git subtree at v2.23.0 r/373

Merge commit '1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5' as 'third_party/git'

1 files changed, 637 insertions, 0 deletions

diff --git a/third_party/git/t/t1404-update-ref-errors.sh b/third_party/git/t/t1404-update-ref-errors.sh
new file mode 100755
index 000000000000..970c5c36b9b5
--- /dev/null
+++ b/third_party/git/t/t1404-update-ref-errors.sh
@@ -0,0 +1,637 @@
+#!/bin/sh
+
+test_description='Test git update-ref error handling'
+. ./test-lib.sh
+
+# Create some references, perhaps run pack-refs --all, then try to
+# create some more references. Ensure that the second creation fails
+# with the correct error message.
+# Usage: test_update_rejected <before> <pack> <create> <error>
+#   <before> is a ws-separated list of refs to create before the test
+#   <pack> (true or false) tells whether to pack the refs before the test
+#   <create> is a list of variables to attempt creating
+#   <error> is a string to look for in the stderr of update-ref.
+# All references are created in the namespace specified by the current
+# value of $prefix.
+test_update_rejected () {
+	before="$1" &&
+	pack="$2" &&
+	create="$3" &&
+	error="$4" &&
+	printf "create $prefix/%s $C\n" $before |
+	git update-ref --stdin &&
+	git for-each-ref $prefix >unchanged &&
+	if $pack
+	then
+		git pack-refs --all
+	fi &&
+	printf "create $prefix/%s $C\n" $create >input &&
+	test_must_fail git update-ref --stdin <input 2>output.err &&
+	test_i18ngrep -F "$error" output.err &&
+	git for-each-ref $prefix >actual &&
+	test_cmp unchanged actual
+}
+
+Q="'"
+
+# Test adding and deleting D/F-conflicting references in a single
+# transaction.
+df_test() {
+	prefix="$1"
+	pack=: symadd=false symdel=false add_del=false addref= delref=
+	shift
+	while test $# -gt 0
+	do
+		case "$1" in
+		--pack)
+			pack="git pack-refs --all"
+			shift
+			;;
+		--sym-add)
+			# Perform the add via a symbolic reference
+			symadd=true
+			shift
+			;;
+		--sym-del)
+			# Perform the del via a symbolic reference
+			symdel=true
+			shift
+			;;
+		--del-add)
+			# Delete first reference then add second
+			add_del=false
+			delref="$prefix/r/$2"
+			addref="$prefix/r/$3"
+			shift 3
+			;;
+		--add-del)
+			# Add first reference then delete second
+			add_del=true
+			addref="$prefix/r/$2"
+			delref="$prefix/r/$3"
+			shift 3
+			;;
+		*)
+			echo 1>&2 "Extra args to df_test: $*"
+			return 1
+			;;
+		esac
+	done
+	git update-ref "$delref" $C &&
+	if $symadd
+	then
+		addname="$prefix/s/symadd" &&
+		git symbolic-ref "$addname" "$addref"
+	else
+		addname="$addref"
+	fi &&
+	if $symdel
+	then
+		delname="$prefix/s/symdel" &&
+		git symbolic-ref "$delname" "$delref"
+	else
+		delname="$delref"
+	fi &&
+	cat >expected-err <<-EOF &&
+	fatal: cannot lock ref $Q$addname$Q: $Q$delref$Q exists; cannot create $Q$addref$Q
+	EOF
+	$pack &&
+	if $add_del
+	then
+		printf "%s\n" "create $addname $D" "delete $delname"
+	else
+		printf "%s\n" "delete $delname" "create $addname $D"
+	fi >commands &&
+	test_must_fail git update-ref --stdin <commands 2>output.err &&
+	test_i18ncmp expected-err output.err &&
+	printf "%s\n" "$C $delref" >expected-refs &&
+	git for-each-ref --format="%(objectname) %(refname)" $prefix/r >actual-refs &&
+	test_cmp expected-refs actual-refs
+}
+
+test_expect_success 'setup' '
+
+	git commit --allow-empty -m Initial &&
+	C=$(git rev-parse HEAD) &&
+	git commit --allow-empty -m Second &&
+	D=$(git rev-parse HEAD) &&
+	git commit --allow-empty -m Third &&
+	E=$(git rev-parse HEAD)
+'
+
+test_expect_success 'existing loose ref is a simple prefix of new' '
+
+	prefix=refs/1l &&
+	test_update_rejected "a c e" false "b c/x d" \
+		"$Q$prefix/c$Q exists; cannot create $Q$prefix/c/x$Q"
+
+'
+
+test_expect_success 'existing packed ref is a simple prefix of new' '
+
+	prefix=refs/1p &&
+	test_update_rejected "a c e" true "b c/x d" \
+		"$Q$prefix/c$Q exists; cannot create $Q$prefix/c/x$Q"
+
+'
+
+test_expect_success 'existing loose ref is a deeper prefix of new' '
+
+	prefix=refs/2l &&
+	test_update_rejected "a c e" false "b c/x/y d" \
+		"$Q$prefix/c$Q exists; cannot create $Q$prefix/c/x/y$Q"
+
+'
+
+test_expect_success 'existing packed ref is a deeper prefix of new' '
+
+	prefix=refs/2p &&
+	test_update_rejected "a c e" true "b c/x/y d" \
+		"$Q$prefix/c$Q exists; cannot create $Q$prefix/c/x/y$Q"
+
+'
+
+test_expect_success 'new ref is a simple prefix of existing loose' '
+
+	prefix=refs/3l &&
+	test_update_rejected "a c/x e" false "b c d" \
+		"$Q$prefix/c/x$Q exists; cannot create $Q$prefix/c$Q"
+
+'
+
+test_expect_success 'new ref is a simple prefix of existing packed' '
+
+	prefix=refs/3p &&
+	test_update_rejected "a c/x e" true "b c d" \
+		"$Q$prefix/c/x$Q exists; cannot create $Q$prefix/c$Q"
+
+'
+
+test_expect_success 'new ref is a deeper prefix of existing loose' '
+
+	prefix=refs/4l &&
+	test_update_rejected "a c/x/y e" false "b c d" \
+		"$Q$prefix/c/x/y$Q exists; cannot create $Q$prefix/c$Q"
+
+'
+
+test_expect_success 'new ref is a deeper prefix of existing packed' '
+
+	prefix=refs/4p &&
+	test_update_rejected "a c/x/y e" true "b c d" \
+		"$Q$prefix/c/x/y$Q exists; cannot create $Q$prefix/c$Q"
+
+'
+
+test_expect_success 'one new ref is a simple prefix of another' '
+
+	prefix=refs/5 &&
+	test_update_rejected "a e" false "b c c/x d" \
+		"cannot process $Q$prefix/c$Q and $Q$prefix/c/x$Q at the same time"
+
+'
+
+test_expect_success 'empty directory should not fool rev-parse' '
+	prefix=refs/e-rev-parse &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	echo "$C" >expected &&
+	git rev-parse $prefix/foo >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'empty directory should not fool for-each-ref' '
+	prefix=refs/e-for-each-ref &&
+	git update-ref $prefix/foo $C &&
+	git for-each-ref $prefix >expected &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	git for-each-ref $prefix >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'empty directory should not fool create' '
+	prefix=refs/e-create &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	printf "create %s $C\n" $prefix/foo |
+	git update-ref --stdin
+'
+
+test_expect_success 'empty directory should not fool verify' '
+	prefix=refs/e-verify &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	printf "verify %s $C\n" $prefix/foo |
+	git update-ref --stdin
+'
+
+test_expect_success 'empty directory should not fool 1-arg update' '
+	prefix=refs/e-update-1 &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	printf "update %s $D\n" $prefix/foo |
+	git update-ref --stdin
+'
+
+test_expect_success 'empty directory should not fool 2-arg update' '
+	prefix=refs/e-update-2 &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	printf "update %s $D $C\n" $prefix/foo |
+	git update-ref --stdin
+'
+
+test_expect_success 'empty directory should not fool 0-arg delete' '
+	prefix=refs/e-delete-0 &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	printf "delete %s\n" $prefix/foo |
+	git update-ref --stdin
+'
+
+test_expect_success 'empty directory should not fool 1-arg delete' '
+	prefix=refs/e-delete-1 &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	mkdir -p .git/$prefix/foo/bar/baz &&
+	printf "delete %s $C\n" $prefix/foo |
+	git update-ref --stdin
+'
+
+test_expect_success 'D/F conflict prevents add long + delete short' '
+	df_test refs/df-al-ds --add-del foo/bar foo
+'
+
+test_expect_success 'D/F conflict prevents add short + delete long' '
+	df_test refs/df-as-dl --add-del foo foo/bar
+'
+
+test_expect_success 'D/F conflict prevents delete long + add short' '
+	df_test refs/df-dl-as --del-add foo/bar foo
+'
+
+test_expect_success 'D/F conflict prevents delete short + add long' '
+	df_test refs/df-ds-al --del-add foo foo/bar
+'
+
+test_expect_success 'D/F conflict prevents add long + delete short packed' '
+	df_test refs/df-al-dsp --pack --add-del foo/bar foo
+'
+
+test_expect_success 'D/F conflict prevents add short + delete long packed' '
+	df_test refs/df-as-dlp --pack --add-del foo foo/bar
+'
+
+test_expect_success 'D/F conflict prevents delete long packed + add short' '
+	df_test refs/df-dlp-as --pack --del-add foo/bar foo
+'
+
+test_expect_success 'D/F conflict prevents delete short packed + add long' '
+	df_test refs/df-dsp-al --pack --del-add foo foo/bar
+'
+
+# Try some combinations involving symbolic refs...
+
+test_expect_success 'D/F conflict prevents indirect add long + delete short' '
+	df_test refs/df-ial-ds --sym-add --add-del foo/bar foo
+'
+
+test_expect_success 'D/F conflict prevents indirect add long + indirect delete short' '
+	df_test refs/df-ial-ids --sym-add --sym-del --add-del foo/bar foo
+'
+
+test_expect_success 'D/F conflict prevents indirect add short + indirect delete long' '
+	df_test refs/df-ias-idl --sym-add --sym-del --add-del foo foo/bar
+'
+
+test_expect_success 'D/F conflict prevents indirect delete long + indirect add short' '
+	df_test refs/df-idl-ias --sym-add --sym-del --del-add foo/bar foo
+'
+
+test_expect_success 'D/F conflict prevents indirect add long + delete short packed' '
+	df_test refs/df-ial-dsp --sym-add --pack --add-del foo/bar foo
+'
+
+test_expect_success 'D/F conflict prevents indirect add long + indirect delete short packed' '
+	df_test refs/df-ial-idsp --sym-add --sym-del --pack --add-del foo/bar foo
+'
+
+test_expect_success 'D/F conflict prevents add long + indirect delete short packed' '
+	df_test refs/df-al-idsp --sym-del --pack --add-del foo/bar foo
+'
+
+test_expect_success 'D/F conflict prevents indirect delete long packed + indirect add short' '
+	df_test refs/df-idlp-ias --sym-add --sym-del --pack --del-add foo/bar foo
+'
+
+# Test various errors when reading the old values of references...
+
+test_expect_success 'missing old value blocks update' '
+	prefix=refs/missing-update &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/foo$Q: unable to resolve reference $Q$prefix/foo$Q
+	EOF
+	printf "%s\n" "update $prefix/foo $E $D" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'incorrect old value blocks update' '
+	prefix=refs/incorrect-update &&
+	git update-ref $prefix/foo $C &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/foo$Q: is at $C but expected $D
+	EOF
+	printf "%s\n" "update $prefix/foo $E $D" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'existing old value blocks create' '
+	prefix=refs/existing-create &&
+	git update-ref $prefix/foo $C &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/foo$Q: reference already exists
+	EOF
+	printf "%s\n" "create $prefix/foo $E" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'incorrect old value blocks delete' '
+	prefix=refs/incorrect-delete &&
+	git update-ref $prefix/foo $C &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/foo$Q: is at $C but expected $D
+	EOF
+	printf "%s\n" "delete $prefix/foo $D" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'missing old value blocks indirect update' '
+	prefix=refs/missing-indirect-update &&
+	git symbolic-ref $prefix/symref $prefix/foo &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/symref$Q: unable to resolve reference $Q$prefix/foo$Q
+	EOF
+	printf "%s\n" "update $prefix/symref $E $D" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'incorrect old value blocks indirect update' '
+	prefix=refs/incorrect-indirect-update &&
+	git symbolic-ref $prefix/symref $prefix/foo &&
+	git update-ref $prefix/foo $C &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/symref$Q: is at $C but expected $D
+	EOF
+	printf "%s\n" "update $prefix/symref $E $D" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'existing old value blocks indirect create' '
+	prefix=refs/existing-indirect-create &&
+	git symbolic-ref $prefix/symref $prefix/foo &&
+	git update-ref $prefix/foo $C &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/symref$Q: reference already exists
+	EOF
+	printf "%s\n" "create $prefix/symref $E" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'incorrect old value blocks indirect delete' '
+	prefix=refs/incorrect-indirect-delete &&
+	git symbolic-ref $prefix/symref $prefix/foo &&
+	git update-ref $prefix/foo $C &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/symref$Q: is at $C but expected $D
+	EOF
+	printf "%s\n" "delete $prefix/symref $D" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'missing old value blocks indirect no-deref update' '
+	prefix=refs/missing-noderef-update &&
+	git symbolic-ref $prefix/symref $prefix/foo &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/symref$Q: reference is missing but expected $D
+	EOF
+	printf "%s\n" "option no-deref" "update $prefix/symref $E $D" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'incorrect old value blocks indirect no-deref update' '
+	prefix=refs/incorrect-noderef-update &&
+	git symbolic-ref $prefix/symref $prefix/foo &&
+	git update-ref $prefix/foo $C &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/symref$Q: is at $C but expected $D
+	EOF
+	printf "%s\n" "option no-deref" "update $prefix/symref $E $D" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'existing old value blocks indirect no-deref create' '
+	prefix=refs/existing-noderef-create &&
+	git symbolic-ref $prefix/symref $prefix/foo &&
+	git update-ref $prefix/foo $C &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/symref$Q: reference already exists
+	EOF
+	printf "%s\n" "option no-deref" "create $prefix/symref $E" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'incorrect old value blocks indirect no-deref delete' '
+	prefix=refs/incorrect-noderef-delete &&
+	git symbolic-ref $prefix/symref $prefix/foo &&
+	git update-ref $prefix/foo $C &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/symref$Q: is at $C but expected $D
+	EOF
+	printf "%s\n" "option no-deref" "delete $prefix/symref $D" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'non-empty directory blocks create' '
+	prefix=refs/ne-create &&
+	mkdir -p .git/$prefix/foo/bar &&
+	: >.git/$prefix/foo/bar/baz.lock &&
+	test_when_finished "rm -f .git/$prefix/foo/bar/baz.lock" &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/foo$Q: there is a non-empty directory $Q.git/$prefix/foo$Q blocking reference $Q$prefix/foo$Q
+	EOF
+	printf "%s\n" "update $prefix/foo $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/foo$Q: unable to resolve reference $Q$prefix/foo$Q
+	EOF
+	printf "%s\n" "update $prefix/foo $D $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'broken reference blocks create' '
+	prefix=refs/broken-create &&
+	mkdir -p .git/$prefix &&
+	echo "gobbledigook" >.git/$prefix/foo &&
+	test_when_finished "rm -f .git/$prefix/foo" &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/foo$Q: unable to resolve reference $Q$prefix/foo$Q: reference broken
+	EOF
+	printf "%s\n" "update $prefix/foo $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/foo$Q: unable to resolve reference $Q$prefix/foo$Q: reference broken
+	EOF
+	printf "%s\n" "update $prefix/foo $D $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'non-empty directory blocks indirect create' '
+	prefix=refs/ne-indirect-create &&
+	git symbolic-ref $prefix/symref $prefix/foo &&
+	mkdir -p .git/$prefix/foo/bar &&
+	: >.git/$prefix/foo/bar/baz.lock &&
+	test_when_finished "rm -f .git/$prefix/foo/bar/baz.lock" &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/symref$Q: there is a non-empty directory $Q.git/$prefix/foo$Q blocking reference $Q$prefix/foo$Q
+	EOF
+	printf "%s\n" "update $prefix/symref $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/symref$Q: unable to resolve reference $Q$prefix/foo$Q
+	EOF
+	printf "%s\n" "update $prefix/symref $D $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'broken reference blocks indirect create' '
+	prefix=refs/broken-indirect-create &&
+	git symbolic-ref $prefix/symref $prefix/foo &&
+	echo "gobbledigook" >.git/$prefix/foo &&
+	test_when_finished "rm -f .git/$prefix/foo" &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/symref$Q: unable to resolve reference $Q$prefix/foo$Q: reference broken
+	EOF
+	printf "%s\n" "update $prefix/symref $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err &&
+	cat >expected <<-EOF &&
+	fatal: cannot lock ref $Q$prefix/symref$Q: unable to resolve reference $Q$prefix/foo$Q: reference broken
+	EOF
+	printf "%s\n" "update $prefix/symref $D $C" |
+	test_must_fail git update-ref --stdin 2>output.err &&
+	test_cmp expected output.err
+'
+
+test_expect_success 'no bogus intermediate values during delete' '
+	prefix=refs/slow-transaction &&
+	# Set up a reference with differing loose and packed versions:
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	git update-ref $prefix/foo $D &&
+	git for-each-ref $prefix >unchanged &&
+	# Now try to update the reference, but hold the `packed-refs` lock
+	# for a while to see what happens while the process is blocked:
+	: >.git/packed-refs.lock &&
+	test_when_finished "rm -f .git/packed-refs.lock" &&
+	{
+		# Note: the following command is intentionally run in the
+		# background. We increase the timeout so that `update-ref`
+		# attempts to acquire the `packed-refs` lock for much longer
+		# than it takes for us to do the check then delete it:
+		git -c core.packedrefstimeout=30000 update-ref -d $prefix/foo &
+	} &&
+	pid2=$! &&
+	# Give update-ref plenty of time to get to the point where it tries
+	# to lock packed-refs:
+	sleep 1 &&
+	# Make sure that update-ref did not complete despite the lock:
+	kill -0 $pid2 &&
+	# Verify that the reference still has its old value:
+	sha1=$(git rev-parse --verify --quiet $prefix/foo || echo undefined) &&
+	case "$sha1" in
+	$D)
+		# This is what we hope for; it means that nothing
+		# user-visible has changed yet.
+		: ;;
+	undefined)
+		# This is not correct; it means the deletion has happened
+		# already even though update-ref should not have been
+		# able to acquire the lock yet.
+		echo "$prefix/foo deleted prematurely" &&
+		break
+		;;
+	$C)
+		# This value should never be seen. Probably the loose
+		# reference has been deleted but the packed reference
+		# is still there:
+		echo "$prefix/foo incorrectly observed to be C" &&
+		break
+		;;
+	*)
+		# WTF?
+		echo "unexpected value observed for $prefix/foo: $sha1" &&
+		break
+		;;
+	esac >out &&
+	rm -f .git/packed-refs.lock &&
+	wait $pid2 &&
+	test_must_be_empty out &&
+	test_must_fail git rev-parse --verify --quiet $prefix/foo
+'
+
+test_expect_success 'delete fails cleanly if packed-refs file is locked' '
+	prefix=refs/locked-packed-refs &&
+	# Set up a reference with differing loose and packed versions:
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	git update-ref $prefix/foo $D &&
+	git for-each-ref $prefix >unchanged &&
+	# Now try to delete it while the `packed-refs` lock is held:
+	: >.git/packed-refs.lock &&
+	test_when_finished "rm -f .git/packed-refs.lock" &&
+	test_must_fail git update-ref -d $prefix/foo >out 2>err &&
+	git for-each-ref $prefix >actual &&
+	test_i18ngrep "Unable to create $Q.*packed-refs.lock$Q: " err &&
+	test_cmp unchanged actual
+'
+
+test_expect_success 'delete fails cleanly if packed-refs.new write fails' '
+	# Setup and expectations are similar to the test above.
+	prefix=refs/failed-packed-refs &&
+	git update-ref $prefix/foo $C &&
+	git pack-refs --all &&
+	git update-ref $prefix/foo $D &&
+	git for-each-ref $prefix >unchanged &&
+	# This should not happen in practice, but it is an easy way to get a
+	# reliable error (we open with create_tempfile(), which uses O_EXCL).
+	: >.git/packed-refs.new &&
+	test_when_finished "rm -f .git/packed-refs.new" &&
+	test_must_fail git update-ref -d $prefix/foo &&
+	git for-each-ref $prefix >actual &&
+	test_cmp unchanged actual
+'
+
+test_done