git-commit: Allow to amend a merge commit that does not change the tree

[git.git] / builtin-commit.c

diff --git a/builtin-commit.c b/builtin-commit.c
index f37a90f078b3e952830abe7ddb83599df2352eff..6c2dc390c451d5942521ddef9f046c5f98097dc3 100644 (file)
--- a/builtin-commit.c
+++ b/builtin-commit.c
@@ -676,6 +676,14 @@ int git_commit_config(const char *k, const char *v)
        return git_status_config(k, v);
 }
 
+static int is_a_merge(const unsigned char *sha1)
+{
+       struct commit *commit = lookup_commit(sha1);
+       if (!commit || parse_commit(commit))
+               die("could not parse HEAD commit");
+       return !!(commit->parents && commit->parents->next);
+}
+
 static const char commit_utf8_warn[] =
 "Warning: commit message does not conform to UTF-8.\n"
 "You may want to amend it after fixing the message, or set the config\n"
@@ -701,7 +709,8 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
                return 1;
        }
 
-       if (!prepare_log_message(index_file, prefix) && !in_merge) {
+       if (!prepare_log_message(index_file, prefix) && !in_merge &&
+           !(amend && is_a_merge(head_sha1))) {
                run_status(stdout, index_file, prefix);
                rollback_index_files();
                unlink(commit_editmsg);