Fix bug with start_recoery(). It calls connect_backend() and then calls PQfinish(NULL) if connect_backend() returns NULL, which is apparently wrong usage of PQfinish(). Actually PQfinish() has been called in connect_backend() in this case. Also fix typo and enhance error message.
Fix bug with start_recoery().
It calls connect_backend() and then calls PQfinish(NULL) if
connect_backend() returns NULL, which is apparently wrong usage of
PQfinish(). Actually PQfinish() has been called in connect_backend()
in this case.
Also fix typo and enhance error message.

treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres,treasure-data/prestogres