get_configured_bridge_by_addr_port_digest() does not work well if digest == NULL
get_configured_bridge_by_addr_port_digest()
returns NULL
if digest is NULL
(the caller doesn't care about the digest) and bridge->identity
set.
Normally, the function should return any bridge with addr/port that matches even if it has an identity digest set.
This bug becomes visible when Tor does a second SOCKS request to the pluggable transport proxy after it has learned the identity digest of a bridge. In that second request, the SOCKS arguments are not passed, since digest == NULL
but bridge->identity
is set.