[PATCH 3/3] commit: Show the committer ident when is different from the parent

["Santi Béjar" <sbejar@gmail.com>]

To remind the committer ident in case it is not what you want
(taken from the gecos field, want to use different ident in
different repositories).

Signed-off-by: Santi Béjar <sbejar@gmail.com>
---
Hi,

  it does not work with the initial commit, I don't know why.
  Even with this:
	if (!commit)
		return NULL;

  Can someone help me? Thanks

 builtin-commit.c  |   30 ++++++++++++++++++++++++++++++
 t/t7502-commit.sh |   12 ++++++++++++
 2 files changed, 42 insertions(+), 0 deletions(-)

diff --git a/builtin-commit.c b/builtin-commit.c
index c51c70f..06582ef 100644
--- a/builtin-commit.c
+++ b/builtin-commit.c
@@ -437,6 +437,29 @@ static void determine_author_info()
 	author_date = date;
 }
 
+const char *get_parent_ident()
+{
+	unsigned char sha1[20];
+	struct commit *commit;
+	const char *a, *lb, *rb, *eol;
+
+
+	get_sha1("HEAD", sha1);
+	commit = lookup_commit_reference(sha1);
+	if (!commit)
+		return NULL;
+
+	a = strstr(commit->buffer, "\ncommitter ");
+
+	lb = strstr(a + 11, " <");
+	rb = strstr(a + 11, "> ");
+	eol = strchr(a + 11, '\n');
+	if (!lb || !rb || !eol)
+		return NULL;
+
+	return xstrndup(a + 11, rb + 1 - (a + 11));
+}
+
 static int prepare_to_commit(const char *index_file, const char *prefix)
 {
 	struct stat statbuf;
@@ -448,6 +471,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix)
 	const char *hook_arg2 = NULL;
 	const char *author_ident;
 	const char *committer_ident;
+	const char *parent_ident;
 
 	if (!no_verify && run_hook(index_file, "pre-commit", NULL))
 		return 0;
@@ -561,6 +585,12 @@ static int prepare_to_commit(const char *index_file, const char *prefix)
 				"# Author:    %s\n",
 				fmt_name(author_name, author_email));
 
+		parent_ident = xstrdup(get_parent_ident());
+		if (strcmp(parent_ident, committer_ident))
+			fprintf(fp,
+				"# Committer: %s\n",
+				committer_ident);
+
 		saved_color_setting = wt_status_use_color;
 		wt_status_use_color = 0;
 		commitable = run_status(fp, index_file, prefix, 1);
diff --git a/t/t7502-commit.sh b/t/t7502-commit.sh
index 95acf4c..96b5dcb 100755
--- a/t/t7502-commit.sh
+++ b/t/t7502-commit.sh
@@ -164,6 +164,18 @@ test_expect_success 'author different from committer' '
 	test_cmp expect actual
 '
 
+GIT_COMMITTER_NAME="C. O. Mitter"
+export GIT_COMMITTER_NAME
+echo "# Committer: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>" >> expect
+
+test_expect_success 'committer different from the parent committer' '
+
+	echo >>negative &&
+	git commit -e -m "sample"
+	head -n 6 .git/COMMIT_EDITMSG >actual &&
+	test_cmp expect actual
+'
+
 pwd=`pwd`
 cat >> .git/FAKE_EDITOR << EOF
 #! /bin/sh
-- 
1.5.5.1.148.g37726