descriptor, the check of the object type doesn't read the __class__ attribute
anymore.  Fix a crash if a class override its __class__ attribute (e.g. a proxy
of the str type).

descriptor, the check of the object type doesn't read the __class__ attribute
anymore.  Fix a crash if a class override its __class__ attribute (e.g. a proxy
of the str type).

check of the object type doesn't read the __class__ attribute anymore.  Fix a
crash if a class override its __class__ attribute (e.g. a proxy of the str
type).

Patch by Lars Michelsen.

Patch by Lars Michelsen.

Patch by Lars Michelsen.

Patch written by Charles-Francois Natali.

and/or change the signal mask of the calling thread.

Fix also tests of test_io using threads and an alarm: use pthread_sigmask() to
ensure that the SIGALRM signal is received by the main thread.

Original patch written by Jean-Paul Calderone.

Possibly redundant once 3.2.1 is out.

merge from 3.2.