merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

1 files changed, 83 insertions, 24 deletions

diff --git a/third_party/git/t/t2018-checkout-branch.sh b/third_party/git/t/t2018-checkout-branch.sh
index 822381dd9d..5f761bc616 100755
--- a/third_party/git/t/t2018-checkout-branch.sh
+++ b/third_party/git/t/t2018-checkout-branch.sh
@@ -1,50 +1,76 @@
 #!/bin/sh
 
-test_description='checkout '
+test_description='checkout'
 
 . ./test-lib.sh
 
-# Arguments: <branch> <sha> [<checkout options>]
+# Arguments: [!] <branch> <oid> [<checkout options>]
 #
 # Runs "git checkout" to switch to <branch>, testing that
 #
 #   1) we are on the specified branch, <branch>;
-#   2) HEAD is <sha>; if <sha> is not specified, the old HEAD is used.
+#   2) HEAD is <oid>; if <oid> is not specified, the old HEAD is used.
 #
 # If <checkout options> is not specified, "git checkout" is run with -b.
-do_checkout() {
+#
+# If the first argument is `!`, "git checkout" is expected to fail when
+# it is run.
+do_checkout () {
+	should_fail= &&
+	if test "x$1" = "x!"
+	then
+		should_fail=yes &&
+		shift
+	fi &&
 	exp_branch=$1 &&
 	exp_ref="refs/heads/$exp_branch" &&
 
-	# if <sha> is not specified, use HEAD.
-	exp_sha=${2:-$(git rev-parse --verify HEAD)} &&
+	# if <oid> is not specified, use HEAD.
+	exp_oid=${2:-$(git rev-parse --verify HEAD)} &&
 
 	# default options for git checkout: -b
-	if [ -z "$3" ]; then
+	if test -z "$3"
+	then
 		opts="-b"
 	else
 		opts="$3"
 	fi
 
-	git checkout $opts $exp_branch $exp_sha &&
+	if test -n "$should_fail"
+	then
+		test_must_fail git checkout $opts $exp_branch $exp_oid
+	else
+		git checkout $opts $exp_branch $exp_oid &&
+		echo "$exp_ref" >ref.expect &&
+		git rev-parse --symbolic-full-name HEAD >ref.actual &&
+		test_cmp ref.expect ref.actual &&
+		echo "$exp_oid" >oid.expect &&
+		git rev-parse --verify HEAD >oid.actual &&
+		test_cmp oid.expect oid.actual
+	fi
+}
 
-	test $exp_ref = $(git rev-parse --symbolic-full-name HEAD) &&
-	test $exp_sha = $(git rev-parse --verify HEAD)
+test_dirty_unmergeable () {
+	test_expect_code 1 git diff --exit-code
 }
 
-test_dirty_unmergeable() {
-	! git diff --exit-code >/dev/null
+test_dirty_unmergeable_discards_changes () {
+	git diff --exit-code
 }
 
-setup_dirty_unmergeable() {
+setup_dirty_unmergeable () {
 	echo >>file1 change2
 }
 
-test_dirty_mergeable() {
-	! git diff --cached --exit-code >/dev/null
+test_dirty_mergeable () {
+	test_expect_code 1 git diff --cached --exit-code
+}
+
+test_dirty_mergeable_discards_changes () {
+	git diff --cached --exit-code
 }
 
-setup_dirty_mergeable() {
+setup_dirty_mergeable () {
 	echo >file2 file2 &&
 	git add file2
 }
@@ -82,7 +108,7 @@ test_expect_success 'checkout -b to a new branch, set to an explicit ref' '
 
 test_expect_success 'checkout -b to a new branch with unmergeable changes fails' '
 	setup_dirty_unmergeable &&
-	test_must_fail do_checkout branch2 $HEAD1 &&
+	do_checkout ! branch2 $HEAD1 &&
 	test_dirty_unmergeable
 '
 
@@ -93,7 +119,7 @@ test_expect_success 'checkout -f -b to a new branch with unmergeable changes dis
 
 	# still dirty and on branch1
 	do_checkout branch2 $HEAD1 "-f -b" &&
-	test_must_fail test_dirty_unmergeable
+	test_dirty_unmergeable_discards_changes
 '
 
 test_expect_success 'checkout -b to a new branch preserves mergeable changes' '
@@ -111,12 +137,12 @@ test_expect_success 'checkout -f -b to a new branch with mergeable changes disca
 	test_when_finished git reset --hard HEAD &&
 	setup_dirty_mergeable &&
 	do_checkout branch2 $HEAD1 "-f -b" &&
-	test_must_fail test_dirty_mergeable
+	test_dirty_mergeable_discards_changes
 '
 
 test_expect_success 'checkout -b to an existing branch fails' '
 	test_when_finished git reset --hard HEAD &&
-	test_must_fail do_checkout branch2 $HEAD2
+	do_checkout ! branch2 $HEAD2
 '
 
 test_expect_success 'checkout -b to @{-1} fails with the right branch name' '
@@ -140,7 +166,8 @@ test_expect_success 'checkout -B to a merge base' '
 '
 
 test_expect_success 'checkout -B to an existing branch from detached HEAD resets branch to HEAD' '
-	git checkout $(git rev-parse --verify HEAD) &&
+	head=$(git rev-parse --verify HEAD) &&
+	git checkout "$head" &&
 
 	do_checkout branch2 "" -B
 '
@@ -155,14 +182,14 @@ test_expect_success 'checkout -B to an existing branch with unmergeable changes
 	git checkout branch1 &&
 
 	setup_dirty_unmergeable &&
-	test_must_fail do_checkout branch2 $HEAD1 -B &&
+	do_checkout ! branch2 $HEAD1 -B &&
 	test_dirty_unmergeable
 '
 
 test_expect_success 'checkout -f -B to an existing branch with unmergeable changes discards changes' '
 	# still dirty and on branch1
 	do_checkout branch2 $HEAD1 "-f -B" &&
-	test_must_fail test_dirty_unmergeable
+	test_dirty_unmergeable_discards_changes
 '
 
 test_expect_success 'checkout -B to an existing branch preserves mergeable changes' '
@@ -179,7 +206,7 @@ test_expect_success 'checkout -f -B to an existing branch with mergeable changes
 
 	setup_dirty_mergeable &&
 	do_checkout branch2 $HEAD1 "-f -B" &&
-	test_must_fail test_dirty_mergeable
+	test_dirty_mergeable_discards_changes
 '
 
 test_expect_success 'checkout -b <describe>' '
@@ -211,4 +238,36 @@ test_expect_success 'checkout -b after clone --no-checkout does a checkout of HE
 	test_path_is_file dest/a.t
 '
 
+test_expect_success 'checkout -b to a new branch preserves mergeable changes despite sparse-checkout' '
+	test_when_finished "
+		git reset --hard &&
+		git checkout branch1-scratch &&
+		test_might_fail git branch -D branch3 &&
+		git config core.sparseCheckout false &&
+		rm .git/info/sparse-checkout" &&
+
+	test_commit file2 &&
+
+	echo stuff >>file1 &&
+	echo file2 >.git/info/sparse-checkout &&
+	git config core.sparseCheckout true &&
+
+	CURHEAD=$(git rev-parse HEAD) &&
+	do_checkout branch3 $CURHEAD &&
+
+	echo file1 >expect &&
+	git diff --name-only >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'checkout -b rejects an invalid start point' '
+	test_must_fail git checkout -b branch4 file1 2>err &&
+	test_i18ngrep "is not a commit" err
+'
+
+test_expect_success 'checkout -b rejects an extra path argument' '
+	test_must_fail git checkout -b branch5 branch1 file1 2>err &&
+	test_i18ngrep "Cannot update paths and switch to branch" err
+'
+
 test_done