Merge branch 'jc/custom-comment-char'

Allow a configuration variable core.commentchar to customize the
character used to comment out the hint lines in the edited text from
the default '#'.

* jc/custom-comment-char:
  Allow custom "comment char"

builtin/fmt-merge-msg.c

@@ -470,7 +470,7 @@ static void fmt_tag_signature(struct strbuf *tagbuf,
 	strbuf_complete_line(tagbuf);
 	if (sig->len) {
 		strbuf_addch(tagbuf, '\n');
-		strbuf_add_lines(tagbuf, "# ", sig->buf, sig->len);
+		strbuf_add_commented_lines(tagbuf, sig->buf, sig->len);
 	}
 }