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, 330 insertions, 0 deletions

diff --git a/third_party/git/t/t6434-merge-recursive-rename-options.sh b/third_party/git/t/t6434-merge-recursive-rename-options.sh
new file mode 100755
index 000000000000..3d9fae68c41c
--- /dev/null
+++ b/third_party/git/t/t6434-merge-recursive-rename-options.sh
@@ -0,0 +1,330 @@
+#!/bin/sh
+
+test_description='merge-recursive rename options
+
+Test rename detection by examining rename/delete conflicts.
+
+* (HEAD -> rename) rename
+| * (master) delete
+|/
+* base
+
+git diff --name-status base master
+D	0-old
+D	1-old
+D	2-old
+D	3-old
+
+git diff --name-status -M01 base rename
+R025    0-old   0-new
+R050    1-old   1-new
+R075    2-old   2-new
+R100    3-old   3-new
+
+Actual similarity indices are parsed from diff output. We rely on the fact that
+they are rounded down (see, e.g., Documentation/diff-generate-patch.txt, which
+mentions this in a different context).
+'
+
+. ./test-lib.sh
+
+get_expected_stages () {
+	git checkout rename -- $1-new &&
+	git ls-files --stage $1-new >expected-stages-undetected-$1 &&
+	sed "s/ 0	/ 2	/" <expected-stages-undetected-$1 \
+		>expected-stages-detected-$1 &&
+	git read-tree -u --reset HEAD
+}
+
+rename_detected () {
+	git ls-files --stage $1-old $1-new >stages-actual-$1 &&
+	test_cmp expected-stages-detected-$1 stages-actual-$1
+}
+
+rename_undetected () {
+	git ls-files --stage $1-old $1-new >stages-actual-$1 &&
+	test_cmp expected-stages-undetected-$1 stages-actual-$1
+}
+
+check_common () {
+	git ls-files --stage >stages-actual &&
+	test_line_count = 4 stages-actual
+}
+
+check_threshold_0 () {
+	check_common &&
+	rename_detected 0 &&
+	rename_detected 1 &&
+	rename_detected 2 &&
+	rename_detected 3
+}
+
+check_threshold_1 () {
+	check_common &&
+	rename_undetected 0 &&
+	rename_detected 1 &&
+	rename_detected 2 &&
+	rename_detected 3
+}
+
+check_threshold_2 () {
+	check_common &&
+	rename_undetected 0 &&
+	rename_undetected 1 &&
+	rename_detected 2 &&
+	rename_detected 3
+}
+
+check_exact_renames () {
+	check_common &&
+	rename_undetected 0 &&
+	rename_undetected 1 &&
+	rename_undetected 2 &&
+	rename_detected 3
+}
+
+check_no_renames () {
+	check_common &&
+	rename_undetected 0 &&
+	rename_undetected 1 &&
+	rename_undetected 2 &&
+	rename_undetected 3
+}
+
+test_expect_success 'setup repo' '
+	cat <<-\EOF >3-old &&
+	33a
+	33b
+	33c
+	33d
+	EOF
+	sed s/33/22/ <3-old >2-old &&
+	sed s/33/11/ <3-old >1-old &&
+	sed s/33/00/ <3-old >0-old &&
+	git add [0-3]-old &&
+	git commit -m base &&
+	git rm [0-3]-old &&
+	git commit -m delete &&
+	git checkout -b rename HEAD^ &&
+	cp 3-old 3-new &&
+	sed 1,1s/./x/ <2-old >2-new &&
+	sed 1,2s/./x/ <1-old >1-new &&
+	sed 1,3s/./x/ <0-old >0-new &&
+	git add [0-3]-new &&
+	git rm [0-3]-old &&
+	git commit -m rename &&
+	get_expected_stages 0 &&
+	get_expected_stages 1 &&
+	get_expected_stages 2 &&
+	get_expected_stages 3 &&
+	check_50="false" &&
+	tail="HEAD^ -- HEAD master"
+'
+
+test_expect_success 'setup thresholds' '
+	git diff --name-status -M01 HEAD^ HEAD >diff-output &&
+	test_debug "cat diff-output" &&
+	test_line_count = 4 diff-output &&
+	grep "R[0-9][0-9][0-9]	\([0-3]\)-old	\1-new" diff-output \
+		>grep-output &&
+	test_cmp diff-output grep-output &&
+	th0=$(sed -n "s/R\(...\)	0-old	0-new/\1/p" <diff-output) &&
+	th1=$(sed -n "s/R\(...\)	1-old	1-new/\1/p" <diff-output) &&
+	th2=$(sed -n "s/R\(...\)	2-old	2-new/\1/p" <diff-output) &&
+	th3=$(sed -n "s/R\(...\)	3-old	3-new/\1/p" <diff-output) &&
+	test "$th0" -lt "$th1" &&
+	test "$th1" -lt "$th2" &&
+	test "$th2" -lt "$th3" &&
+	test "$th3" = 100 &&
+	if test 50 -le "$th0"
+	then
+		check_50=check_threshold_0
+	elif test 50 -le "$th1"
+	then
+		check_50=check_threshold_1
+	elif test 50 -le "$th2"
+	then
+		check_50=check_threshold_2
+	fi &&
+	th0="$th0%" &&
+	th1="$th1%" &&
+	th2="$th2%" &&
+	th3="$th3%"
+'
+
+test_expect_success 'assumption for tests: rename detection with diff' '
+	git diff --name-status -M$th0 --diff-filter=R HEAD^ HEAD \
+		>diff-output-0 &&
+	git diff --name-status -M$th1 --diff-filter=R HEAD^ HEAD \
+		>diff-output-1 &&
+	git diff --name-status -M$th2 --diff-filter=R HEAD^ HEAD \
+		>diff-output-2 &&
+	git diff --name-status -M100% --diff-filter=R HEAD^ HEAD \
+		>diff-output-3 &&
+	test_line_count = 4 diff-output-0 &&
+	test_line_count = 3 diff-output-1 &&
+	test_line_count = 2 diff-output-2 &&
+	test_line_count = 1 diff-output-3
+'
+
+test_expect_success 'default similarity threshold is 50%' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive $tail &&
+	$check_50
+'
+
+test_expect_success 'low rename threshold' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --find-renames=$th0 $tail &&
+	check_threshold_0
+'
+
+test_expect_success 'medium rename threshold' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --find-renames=$th1 $tail &&
+	check_threshold_1
+'
+
+test_expect_success 'high rename threshold' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --find-renames=$th2 $tail &&
+	check_threshold_2
+'
+
+test_expect_success 'exact renames only' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --find-renames=100% $tail &&
+	check_exact_renames
+'
+
+test_expect_success 'rename threshold is truncated' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --find-renames=200% $tail &&
+	check_exact_renames
+'
+
+test_expect_success 'disabled rename detection' '
+	git read-tree --reset -u HEAD &&
+	git merge-recursive --no-renames $tail &&
+	check_no_renames
+'
+
+test_expect_success 'last wins in --find-renames=<m> --find-renames=<n>' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive \
+		--find-renames=$th0 --find-renames=$th2 $tail &&
+	check_threshold_2
+'
+
+test_expect_success '--find-renames resets threshold' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive \
+		--find-renames=$th0 --find-renames $tail &&
+	$check_50
+'
+
+test_expect_success 'last wins in --no-renames --find-renames' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --no-renames --find-renames $tail &&
+	$check_50
+'
+
+test_expect_success 'last wins in --find-renames --no-renames' '
+	git read-tree --reset -u HEAD &&
+	git merge-recursive --find-renames --no-renames $tail &&
+	check_no_renames
+'
+
+test_expect_success 'assumption for further tests: trivial merge succeeds' '
+	git read-tree --reset -u HEAD &&
+	git merge-recursive HEAD -- HEAD HEAD &&
+	git diff --quiet --cached &&
+	git merge-recursive --find-renames=$th0 HEAD -- HEAD HEAD &&
+	git diff --quiet --cached &&
+	git merge-recursive --find-renames=$th2 HEAD -- HEAD HEAD &&
+	git diff --quiet --cached &&
+	git merge-recursive --find-renames=100% HEAD -- HEAD HEAD &&
+	git diff --quiet --cached &&
+	git merge-recursive --no-renames HEAD -- HEAD HEAD &&
+	git diff --quiet --cached
+'
+
+test_expect_success '--find-renames rejects negative argument' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --find-renames=-25 \
+		HEAD -- HEAD HEAD &&
+	git diff --quiet --cached
+'
+
+test_expect_success '--find-renames rejects non-numbers' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --find-renames=0xf \
+		HEAD -- HEAD HEAD &&
+	git diff --quiet --cached
+'
+
+test_expect_success 'rename-threshold=<n> is a synonym for find-renames=<n>' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --rename-threshold=$th0 $tail &&
+	check_threshold_0
+'
+
+test_expect_success 'last wins in --no-renames --rename-threshold=<n>' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --no-renames --rename-threshold=$th0 $tail &&
+	check_threshold_0
+'
+
+test_expect_success 'last wins in --rename-threshold=<n> --no-renames' '
+	git read-tree --reset -u HEAD &&
+	git merge-recursive --rename-threshold=$th0 --no-renames $tail &&
+	check_no_renames
+'
+
+test_expect_success '--rename-threshold=<n> rejects negative argument' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --rename-threshold=-25 \
+		HEAD -- HEAD HEAD &&
+	git diff --quiet --cached
+'
+
+test_expect_success '--rename-threshold=<n> rejects non-numbers' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive --rename-threshold=0xf \
+		HEAD -- HEAD HEAD &&
+	git diff --quiet --cached
+'
+
+test_expect_success 'last wins in --rename-threshold=<m> --find-renames=<n>' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive \
+		--rename-threshold=$th0 --find-renames=$th2 $tail &&
+	check_threshold_2
+'
+
+test_expect_success 'last wins in --find-renames=<m> --rename-threshold=<n>' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git merge-recursive \
+		--find-renames=$th2 --rename-threshold=$th0 $tail &&
+	check_threshold_0
+'
+
+test_expect_success 'merge.renames disables rename detection' '
+	git read-tree --reset -u HEAD &&
+	git -c merge.renames=false merge-recursive $tail &&
+	check_no_renames
+'
+
+test_expect_success 'merge.renames defaults to diff.renames' '
+	git read-tree --reset -u HEAD &&
+	git -c diff.renames=false merge-recursive $tail &&
+	check_no_renames
+'
+
+test_expect_success 'merge.renames overrides diff.renames' '
+	git read-tree --reset -u HEAD &&
+	test_must_fail git -c diff.renames=false -c merge.renames=true merge-recursive $tail &&
+	$check_50
+'
+
+test_done