Teach "git apply" to prepend a prefix with "--root=<root>"

With "git apply --root=<root>", all file names in the patch are prepended
with <root>.  If a "-p" value was given, the paths are stripped _before_
prepending <root>.

Wished for by HPA.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/t/t4128-apply-root.sh b/t/t4128-apply-root.sh
new file mode 100755
index 000000000..80b5af2b4
--- /dev/null
+++ b/t/t4128-apply-root.sh
@@ -0,0 +1,32 @@
+#!/bin/sh
+
+test_description='apply same filename'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+
+	mkdir -p some/sub/dir &&
+	echo Hello > some/sub/dir/file &&
+	git add some/sub/dir/file
+
+'
+
+cat > patch << EOF
+diff a/bla/blub/dir/file b/bla/blub/dir/file
+--- a/bla/blub/dir/file
++++ b/bla/blub/dir/file
+@@ -1,1 +1,1 @@
+-Hello
++Bello
+EOF
+
+test_expect_success 'apply --root -p --index' '
+
+	git apply --root=some/sub -p3 --index patch &&
+	test Bello = $(git show :some/sub/dir/file) &&
+	test Bello = $(cat some/sub/dir/file)
+
+'
+
+test_done