GDBusConnection leaks its GCredentials

GDBusConnection leaks its GCredentials

==7269== 144 bytes in 6 blocks are definitely lost in loss record 1,282 of 1,325
==7269==    at 0x4005BDC: malloc (vg_replace_malloc.c:195)
==7269==    by 0x4056B74: g_malloc (gmem.c:164)
==7269==    by 0x406EDB6: g_slice_alloc (gslice.c:842)
==7269==    by 0x406EDFB: g_slice_alloc0 (gslice.c:854)
==7269==    by 0x413C627: g_type_create_instance (gtype.c:1867)
==7269==    by 0x412276A: g_object_constructor (gobject.c:1480)
==7269==    by 0x4121E5D: g_object_newv (gobject.c:1264)
==7269==    by 0x4121BD3: g_object_new (gobject.c:1176)
==7269==    by 0x417CFB9: g_credentials_new (gcredentials.c:156)
==7269==    by 0x41D9DBC: g_unix_credentials_message_deserialize (gunixcredentialsmessage.c:149)
==7269==    by 0x41C422C: g_socket_control_message_deserialize (gsocketcontrolmessage.c:198)
==7269==    by 0x41BFCE3: g_socket_receive_message (gsocket.c:3289)
==7269==    by 0x41D99CE: g_unix_connection_receive_credentials (gunixconnection.c:476)
==7269==    by 0x41FA829: _g_dbus_auth_run_server (gdbusauth.c:987)
==7269==    by 0x4205DDB: initable_init (gdbusconnection.c:2196)

Bug #629689.