SF bug #438295: [Windows] __init__.py cause strange behavior Probable fix (the bug report doesn't have enough info to say for sure). find_init_module(): Insist on a case-sensitive match for __init__ files. Given __INIT__.PY instead, find_init_module() thought that was fine, but the later attempt to do find_module("__INIT__.PY") didn't and its caller silently suppressed the resulting ImportError. Now find_init_module() refuses to accept __INIT__.PY to begin with. Bugfix candidate; specific to platforms with case-insensitive filesystems.