I am part of a team where many use the py-xmlrpc module. However some would experience segfaults where others would not on similar configurations. After a bit of debugging, I see that when you initialize a server object, it constructs a rpcSource object. Unless the an errorHandler callback is registered, the variables used to indicate prescense of an errorhandler remain uninitialized. If for instance the uninitialized soure->onErrType gets the value 1 (which also happens to be the macro ONERR_TYPE_PY), the server object will try to increment the reference count of a non-existent method object, hence a segfault.
I would recommend that you add the following line in the rpcSourceNew function in rpcSource.c:
sp->onErrType = ONERR_TYPE_DEF;
or in a better way deal with servers that do not have error handlers registered.