> Here is one stacktrace I just got with the faulthandler installed. It does not show in the trace any 3rd-party module so can I conclude it is a core python bug? Just recompiling with "-ggdb" so eventually will have better stacktraces.

I'm a C noob but I think one can't conclude that it is a core python bug as the ref count could have been messed with, then sometime later the error may occur and GDB's stacktrace will show the latter.
Or in pseudo-code:

mess_with_ref_count() # In 3rd party code
non_3rd_party_code() #the error may occur here, after the refcount was messed with, and gdb will show this function in the stack trace

BTW, run ./configure with the --with-pydebug option, that makes Python perform extra checks on refcounts and other things [0]

^0 http://docs.python.org/devguide/setup.html#compiling-for-debugging