Initial patch by Zachary Ware.

Initial patch by Zachary Ware.

Thanks to George Yoshida.

Thanks to George Yoshida.

Thanks to George Yoshida.

Thanks to Daniel Müllner from docs@

Thanks to Daniel Müllner from docs@

Thanks to Daniel Müllner from docs@

Patch by Stephen Tonkin.

Patch by Stephen Tonkin.

Calling OS functions can fail with errors other than FileNotFoundError: a
FreeBSD buildbot fails for example with a PermissionError.

... (unsigned long and unsigned int) to avoid an undefined behaviour with
Py_TPFLAGS_TYPE_SUBCLASS ((1 << 31). PyType_GetFlags() result type is now
unsigned too (unsigned long, instead of long).

Patch written by Serhiy Storchaka.