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, 152 insertions, 0 deletions

diff --git a/third_party/git/t/t6409-merge-subtree.sh b/third_party/git/t/t6409-merge-subtree.sh
new file mode 100755
index 000000000000..b8e8b6f6429e
--- /dev/null
+++ b/third_party/git/t/t6409-merge-subtree.sh
@@ -0,0 +1,152 @@
+#!/bin/sh
+
+test_description='subtree merge strategy'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+
+	s="1 2 3 4 5 6 7 8" &&
+	for i in $s; do echo $i; done >hello &&
+	git add hello &&
+	git commit -m initial &&
+	git checkout -b side &&
+	echo >>hello world &&
+	git add hello &&
+	git commit -m second &&
+	git checkout master &&
+	for i in mundo $s; do echo $i; done >hello &&
+	git add hello &&
+	git commit -m master
+
+'
+
+test_expect_success 'subtree available and works like recursive' '
+
+	git merge -s subtree side &&
+	for i in mundo $s world; do echo $i; done >expect &&
+	test_cmp expect hello
+
+'
+
+test_expect_success 'setup branch sub' '
+	git checkout --orphan sub &&
+	git rm -rf . &&
+	test_commit foo
+'
+
+test_expect_success 'setup topic branch' '
+	git checkout -b topic master &&
+	git merge -s ours --no-commit --allow-unrelated-histories sub &&
+	git read-tree --prefix=dir/ -u sub &&
+	git commit -m "initial merge of sub into topic" &&
+	test_path_is_file dir/foo.t &&
+	test_path_is_file hello
+'
+
+test_expect_success 'update branch sub' '
+	git checkout sub &&
+	test_commit bar
+'
+
+test_expect_success 'update topic branch' '
+	git checkout topic &&
+	git merge -s subtree sub -m "second merge of sub into topic" &&
+	test_path_is_file dir/bar.t &&
+	test_path_is_file dir/foo.t &&
+	test_path_is_file hello
+'
+
+test_expect_success 'setup' '
+	mkdir git-gui &&
+	cd git-gui &&
+	git init &&
+	echo git-gui > git-gui.sh &&
+	o1=$(git hash-object git-gui.sh) &&
+	git add git-gui.sh &&
+	git commit -m "initial git-gui" &&
+	cd .. &&
+	mkdir git &&
+	cd git &&
+	git init &&
+	echo git >git.c &&
+	o2=$(git hash-object git.c) &&
+	git add git.c &&
+	git commit -m "initial git"
+'
+
+test_expect_success 'initial merge' '
+	git remote add -f gui ../git-gui &&
+	git merge -s ours --no-commit --allow-unrelated-histories gui/master &&
+	git read-tree --prefix=git-gui/ -u gui/master &&
+	git commit -m "Merge git-gui as our subdirectory" &&
+	git checkout -b work &&
+	git ls-files -s >actual &&
+	(
+		echo "100644 $o1 0	git-gui/git-gui.sh" &&
+		echo "100644 $o2 0	git.c"
+	) >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'merge update' '
+	cd ../git-gui &&
+	echo git-gui2 > git-gui.sh &&
+	o3=$(git hash-object git-gui.sh) &&
+	git add git-gui.sh &&
+	git checkout -b topic_2 &&
+	git commit -m "update git-gui" &&
+	cd ../git &&
+	git pull -s subtree gui topic_2 &&
+	git ls-files -s >actual &&
+	(
+		echo "100644 $o3 0	git-gui/git-gui.sh" &&
+		echo "100644 $o2 0	git.c"
+	) >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'initial ambiguous subtree' '
+	cd ../git &&
+	git reset --hard master &&
+	git checkout -b topic_2 &&
+	git merge -s ours --no-commit gui/master &&
+	git read-tree --prefix=git-gui2/ -u gui/master &&
+	git commit -m "Merge git-gui2 as our subdirectory" &&
+	git checkout -b work2 &&
+	git ls-files -s >actual &&
+	(
+		echo "100644 $o1 0	git-gui/git-gui.sh" &&
+		echo "100644 $o1 0	git-gui2/git-gui.sh" &&
+		echo "100644 $o2 0	git.c"
+	) >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'merge using explicit' '
+	cd ../git &&
+	git reset --hard topic_2 &&
+	git pull -Xsubtree=git-gui gui topic_2 &&
+	git ls-files -s >actual &&
+	(
+		echo "100644 $o3 0	git-gui/git-gui.sh" &&
+		echo "100644 $o1 0	git-gui2/git-gui.sh" &&
+		echo "100644 $o2 0	git.c"
+	) >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'merge2 using explicit' '
+	cd ../git &&
+	git reset --hard topic_2 &&
+	git pull -Xsubtree=git-gui2 gui topic_2 &&
+	git ls-files -s >actual &&
+	(
+		echo "100644 $o1 0	git-gui/git-gui.sh" &&
+		echo "100644 $o3 0	git-gui2/git-gui.sh" &&
+		echo "100644 $o2 0	git.c"
+	) >expected &&
+	test_cmp expected actual
+'
+
+test_done