assertion '_PyGObject_API != NULL' failed
We never call pygobject_init(), so this assertion fails (at least for me) in gplp_func_exec_action(). I actually do not understand why this test is needed there.
If we want to keep it, we might replace by:
if (_PyGObject_API == NULL) { pygobject_init(); g__return_if_fail (_PyGObject_API != NULL); }
We have two other such tests in python-loader.c which might be replaced as well.