Return from connection_exit_connect() if we failed to create CONNECTED payload

882b389668067a29bb539d0f5bd5cb2f83b93012 forgets to return from connection_exit_connect() if connected_cell_format_payload() fails: https://gitweb.torproject.org/tor.git/blob/HEAD:/src/or/connection_edge.c#l2613

I'm not too familiar with the high-level logic of this code, but this looks buggy.