Some non-compliant MUAs use '.'s, so by the Postel Principle we should
accept them.  Patch by Thomas Herve.

non-semaphore implementation of locks is used under POSIX.

Issue 9856: Change object.__format__ with a non-empty format string from a PendingDeprecationWarning to a DeprecationWarning.

Thanks to SilenGhost for catching this.

Issue 11131: Fix sign of zero result on decimal.Decimal plus and minus operations in ROUND_FLOOR rounding mode.

fail under tracing.