commit.c: add in_merge_bases_many()

Similar to in_merge_bases(commit, other) that returns true when
commit is an ancestor (i.e. in the merge bases between the two) of
the other commit, in_merge_bases_many(commit, n_other, other[])
checks if commit is an ancestor of any of the other[] commits.

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

commit.c

@@ -858,24 +858,36 @@ int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 	return 0;
 }
 
+/*
+ * Is "commit" an ancestor of one of the "references"?
+ */
+int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit **reference)
+{
+	struct commit_list *bases;
+	int ret = 0, i;
+
+	if (parse_commit(commit))
+		return ret;
+	for (i = 0; i < nr_reference; i++)
+		if (parse_commit(reference[i]))
+			return ret;
+
+	bases = paint_down_to_common(commit, nr_reference, reference);
+	if (commit->object.flags & PARENT2)
+		ret = 1;
+	clear_commit_marks(commit, all_flags);
+	for (i = 0; i < nr_reference; i++)
+		clear_commit_marks(reference[i], all_flags);
+	free_commit_list(bases);
+	return ret;
+}
+
 /*
  * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
  */
 int in_merge_bases(struct commit *commit, struct commit *reference)
 {
-	struct commit_list *bases;
-	int ret = 0;
-
-	if (parse_commit(commit) || parse_commit(reference))
-		return ret;
-
-	bases = paint_down_to_common(commit, 1, &reference);
-	if (commit->object.flags & PARENT2)
-		ret = 1;
-	clear_commit_marks(commit, all_flags);
-	clear_commit_marks(reference, all_flags);
-	free_commit_list(bases);
-	return ret;
+	return in_merge_bases_many(commit, 1, &reference);
 }
 
 struct commit_list *reduce_heads(struct commit_list *heads)

commit.h

@@ -171,6 +171,7 @@ extern struct commit_list *get_shallow_commits(struct object_array *heads,
 
 int is_descendant_of(struct commit *, struct commit_list *);
 int in_merge_bases(struct commit *, struct commit *);
+int in_merge_bases_many(struct commit *, int, struct commit **);
 
 extern int interactive_add(int argc, const char **argv, const char *prefix, int patch);
 extern int run_add_interactive(const char *revision, const char *patch_mode,