Move create_notes_commit() from notes-merge.c into notes-utils.c

create_notes_commit() is needed by both the notes-merge code, and by
commit_notes() in notes-utils. Since it is generally useful, and not
bound to the notes-merge machinery, we move it from (the more specific)
notes-merge to (the more general) notes-utils.

Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/notes-utils.c b/notes-utils.c
index 5c9c976..9107c37 100644
--- a/notes-utils.c
+++ b/notes-utils.c
@@ -2,7 +2,32 @@
 #include "commit.h"
 #include "refs.h"
 #include "notes-utils.h"
-#include "notes-merge.h" /* for create_notes_commit() */
+
+void create_notes_commit(struct notes_tree *t, struct commit_list *parents,
+			 const struct strbuf *msg, unsigned char *result_sha1)
+{
+	unsigned char tree_sha1[20];
+
+	assert(t->initialized);
+
+	if (write_notes_tree(t, tree_sha1))
+		die("Failed to write notes tree to database");
+
+	if (!parents) {
+		/* Deduce parent commit from t->ref */
+		unsigned char parent_sha1[20];
+		if (!read_ref(t->ref, parent_sha1)) {
+			struct commit *parent = lookup_commit(parent_sha1);
+			if (!parent || parse_commit(parent))
+				die("Failed to find/parse commit %s", t->ref);
+			commit_list_insert(parent, &parents);
+		}
+		/* else: t->ref points to nothing, assume root/orphan commit */
+	}
+
+	if (commit_tree(msg, tree_sha1, parents, result_sha1, NULL, NULL))
+		die("Failed to commit notes tree to database");
+}
 
 void commit_notes(struct notes_tree *t, const char *msg)
 {