ref_transaction_commit: bail out on failure to remove a ref

When removal of a loose or packed ref fails, bail out instead of trying to finish the transaction. This way, a single error message can be printed (instead of multiple messages being concatenated by mistake) and the operator can try to solve the underlying problem before there is a chance to muck things up even more. In particular, when git fails to remove a ref, git goes on to try to delete the reflog. Exiting early lets us keep the reflog. When git succeeds in deleting a ref A and fails to remove a ref B, it goes on to try to delete both reflogs. It would be better to just remove the reflog for A, but that would be a more invasive change. Failing early means we keep both reflogs, which puts the operator in a good position to understand the problem and recover. A long term goal is to avoid these problems altogether and roll back the transaction on failure. That kind of transactionality will have to wait for a later series (the plan for which is to make all destructive work happen in a single update of the packed-refs file). Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Reviewed-by: Ronnie Sahlberg <sahlberg@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>