connection: _get_fd() always returns a valid fd
connection: _get_fd() always returns a valid fd

It is only closed by connection_destroy(), at which point you
can't call _get_fd() anymore. Returning a valid fd doesn't mean
the connection is still working - for that, one can call _get_error().
But _get_fd() should normally get called after establishing the
connection, then poll on it, and check the return codes on
_read(), _dispatch() etc to know if/when the connection fails.

Signed-off-by: Emilio Pozuelo Monfort <74af59c529c33a30889589bc73d19ca9a6fb0e6a@collabora.co.uk>

waltham/waltham,waltham/waltham