git-codereview: fix commitmsg hook when verbose

If the commit message is verbose it shows the diff being committed. This
can be shown by either `git commit --verbose` or setting the following
in your git config:

	[commit]
		verbose = true

The diff is uncomented and shown after a "everything below will be
removed" comment section. Identify it and do remove everything under it,
as otherwise the diff would get mixed up with the commit message.

Fixes golang/go#16376.

Change-Id: Ia69aeaf36a1c8471da423a142fb233168d455a5d
Reviewed-on: https://go-review.googlesource.com/25342
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

2 files changed, 14 insertions, 1 deletions

diff --git a/git-codereview/hook.go b/git-codereview/hook.go
index 63e8fd7..0e8f075 100644
--- a/git-codereview/hook.go
+++ b/git-codereview/hook.go
@@ -212,6 +212,8 @@ func hookCommitMsg(args []string) {
 var (
 	fixupBang  = []byte("fixup!")
 	squashBang = []byte("squash!")
+
+	ignoreBelow = []byte("\n# ------------------------ >8 ------------------------\n")
 )
 
 // isFixup reports whether text is a Git fixup! or squash! commit,
@@ -220,8 +222,14 @@ func isFixup(text []byte) bool {
 	return bytes.HasPrefix(text, fixupBang) || bytes.HasPrefix(text, squashBang)
 }
 
-// stripComments strips lines that begin with "#".
+// stripComments strips lines that begin with "#" and removes the
+// "everything below will be removed" section containing the diff when
+// using commit --verbose.
 func stripComments(in []byte) []byte {
+	// Issue 16376
+	if i := bytes.Index(in, ignoreBelow); i >= 0 {
+		in = in[:i+1]
+	}
 	return regexp.MustCompile(`(?m)^#.*\n`).ReplaceAll(in, nil)
 }
 
diff --git a/git-codereview/hook_test.go b/git-codereview/hook_test.go
index ca1fff3..0d171c0 100644
--- a/git-codereview/hook_test.go
+++ b/git-codereview/hook_test.go
@@ -66,6 +66,11 @@ func TestHookCommitMsg(t *testing.T) {
 		{in: "all: gofmt\nahhh", want: "all: gofmt\n\nahhh"},
 		{in: "all: gofmt\n\nahhh", want: "all: gofmt\n\nahhh"},
 		{in: "all: gofmt\n\n\nahhh", want: "all: gofmt\n\n\nahhh"},
+		// Issue 16376
+		{
+			in:   "all: gofmt\n# ------------------------ >8 ------------------------\ndiff",
+			want: "all: gofmt\n",
+		},
 	}
 	for _, tt := range rewrites {
 		write(t, gt.client+"/in.txt", tt.in)