commit: copy merged signed tags to headers of merge commit

Now MERGE_HEAD records the tag objects without peeling, we could record
the result of manual conflict resolution via "git commit" without losing
the tag information. Introduce a new "mergetag" multi-line header field to
the commit object, and use it to store the entire contents of each signed
tag merged.

A commit header that has a multi-line payload begins with the header tag
(e.g. "mergetag" in this case), SP, the first line of payload, LF, and all
the remaining lines have a SP inserted at the beginning.

In hindsight, it would have been better to make "merge --continue" as the
way to continue from such an interrupted merge, not "commit", but this is
a backward compatibility baggage we would need to carry around for now.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/builtin/commit.c b/builtin/commit.c
index c46f2d18e1..4688a738f7 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1425,7 +1425,6 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 			pptr = &commit_list_insert(c->item, pptr)->next;
 	} else if (whence == FROM_MERGE) {
 		struct strbuf m = STRBUF_INIT;
-		struct commit *commit;
 		FILE *fp;
 
 		if (!reflog_msg)
@@ -1436,11 +1435,12 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 			die_errno(_("could not open '%s' for reading"),
 				  git_path("MERGE_HEAD"));
 		while (strbuf_getline(&m, fp, '\n') != EOF) {
-			unsigned char sha1[20];
-			if (get_sha1_hex(m.buf, sha1) < 0)
+			struct commit *parent;
+
+			parent = get_merge_parent(m.buf);
+			if (!parent)
 				die(_("Corrupt MERGE_HEAD file (%s)"), m.buf);
-			commit = lookup_commit_or_die(sha1, "MERGE_HEAD");
-			pptr = &commit_list_insert(commit, pptr)->next;
+			pptr = &commit_list_insert(parent, pptr)->next;
 		}
 		fclose(fp);
 		strbuf_release(&m);