Previously, on service disappeared event the list of the known
proxy objects was cleared, but pointers to the default entity
per command family wasn’t reset. Reset default entities for
the command families to remove the dead pointers to the deleted
proxy objects.
==1325== Invalid read of size 8
==1325== at 0x4055D4: proxy_interface_is_same (dbus-proxy.c:439)
==1325== by 0x407C28: match_by_partial_name (network.c:220)
==1325== by 0x40547C: proxy_interface_find_all (dbus-proxy.c:424)
==1325== by 0x405592: proxy_property_str_completion (dbus-proxy.c:153)
==1325== by 0x407DA9: network_name_completion (network.c:241)
==1325== by 0x4E596D5: rl_completion_matches (in /usr/lib64/libreadline.so.7.0)
The code would assume that a command with argc >= 3 would always be
composed of <family name> <entity> <command> and thus
"known-networks forget <ssid>" could not be executed. Instead of
checking argc >= 3 check whether command->entity is non-NULL.
This allows to inspect the cmd line for the existence of a provided
token. This enables the completers to look back to what was entered
before them and make decisions based on that information. For
example, this can be used in completion of the property values
to identify the property for which the value is being completed.
