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, 103 insertions, 0 deletions

diff --git a/third_party/git/t/t6412-merge-large-rename.sh b/third_party/git/t/t6412-merge-large-rename.sh
new file mode 100755
index 000000000000..80777386dc69
--- /dev/null
+++ b/third_party/git/t/t6412-merge-large-rename.sh
@@ -0,0 +1,103 @@
+#!/bin/sh
+
+test_description='merging with large rename matrix'
+. ./test-lib.sh
+
+count() {
+	i=1
+	while test $i -le $1; do
+		echo $i
+		i=$(($i + 1))
+	done
+}
+
+test_expect_success 'setup (initial)' '
+	touch file &&
+	git add . &&
+	git commit -m initial &&
+	git tag initial
+'
+
+make_text() {
+	echo $1: $2
+	for i in $(count 20); do
+		echo $1: $i
+	done
+	echo $1: $3
+}
+
+test_rename() {
+	test_expect_success "rename ($1, $2)" '
+	n='$1' &&
+	expect='$2' &&
+	git checkout -f master &&
+	test_might_fail git branch -D test$n &&
+	git reset --hard initial &&
+	for i in $(count $n); do
+		make_text $i initial initial >$i
+	done &&
+	git add . &&
+	git commit -m add=$n &&
+	for i in $(count $n); do
+		make_text $i changed initial >$i
+	done &&
+	git commit -a -m change=$n &&
+	git checkout -b test$n HEAD^ &&
+	for i in $(count $n); do
+		git rm $i
+		make_text $i initial changed >$i.moved
+	done &&
+	git add . &&
+	git commit -m change+rename=$n &&
+	case "$expect" in
+		ok) git merge master ;;
+		 *) test_must_fail git merge master ;;
+	esac
+	'
+}
+
+test_rename 5 ok
+
+test_expect_success 'set diff.renamelimit to 4' '
+	git config diff.renamelimit 4
+'
+test_rename 4 ok
+test_rename 5 fail
+
+test_expect_success 'set merge.renamelimit to 5' '
+	git config merge.renamelimit 5
+'
+test_rename 5 ok
+test_rename 6 fail
+
+test_expect_success 'setup large simple rename' '
+	git config --unset merge.renamelimit &&
+	git config --unset diff.renamelimit &&
+
+	git reset --hard initial &&
+	for i in $(count 200); do
+		make_text foo bar baz >$i
+	done &&
+	git add . &&
+	git commit -m create-files &&
+
+	git branch simple-change &&
+	git checkout -b simple-rename &&
+
+	mkdir builtin &&
+	git mv [0-9]* builtin/ &&
+	git commit -m renamed &&
+
+	git checkout simple-change &&
+	>unrelated-change &&
+	git add unrelated-change &&
+	git commit -m unrelated-change
+'
+
+test_expect_success 'massive simple rename does not spam added files' '
+	sane_unset GIT_MERGE_VERBOSITY &&
+	git merge --no-stat simple-rename | grep -v Removing >output &&
+	test_line_count -lt 5 output
+'
+
+test_done