test-contacts/by_handle_again: don't SEGV on failure
test-contacts/by_handle_again: don't SEGV on failure

If this test regresses (perhaps because some nefarious developer finds
that it fails for many features other than ALIAS, and systematically
tries them all), it should fail with a reasonable assertion, rather than
a segmentation fault. Thus, our first assertion should be that the
second call to tp_connection_get_contacts_by_handle() did not return an
error, rather than trying to make assertions which will dereference NULL
pointers if the call fails.

Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib