Merge branch 'jk/push-delete-ref-error-message' into maint

The error message from "git push $there :bogo" (and its equivalent
"git push $there --delete bogo") mentioned that we tried and failed
to guess what ref is being deleted based on the LHS of the refspec,
which we don't.

* jk/push-delete-ref-error-message:
  push: don't guess at qualifying remote refs on deletion

remote.c

@@ -1100,6 +1100,9 @@ static int match_explicit(struct ref *src, struct ref *dst,
 	case 0:
 		if (!memcmp(dst_value, "refs/", 5))
 			matched_dst = make_linked_ref(dst_value, dst_tail);
+		else if (is_null_sha1(matched_src->new_sha1))
+			error("unable to delete '%s': remote ref does not exist",
+			      dst_value);
 		else if ((dst_guess = guess_ref(dst_value, matched_src)))
 			matched_dst = make_linked_ref(dst_guess, dst_tail);
 		else