Merge branch 'mg/commit-author-no-match-malformed-message' into maint

The error message from "git commit", when a non-existing author
name was given as value to the "--author=" parameter, has been
reworded to avoid misunderstanding.

* mg/commit-author-no-match-malformed-message:
  commit: reword --author error message

builtin/commit.c

@@ -1050,7 +1050,7 @@ static const char *find_author_by_nickname(const char *name)
 		clear_mailmap(&mailmap);
 		return strbuf_detach(&buf, NULL);
 	}
-	die(_("No existing author found with '%s'"), name);
+	die(_("--author '%s' is not 'Name <email>' and matches no existing author"), name);
 }