locking: fix ExclusiveLock race condition bug, fixes#4923
- ExclusiveLock is now based on os.rename instead of os.mkdir.
- catch FileNotFoundError observed under race condition in ExclusiveLock.release()
and .kill_stale_lock()
- added TestExclusiveLock.test_race_condition() which reveals issue #4923
- updated docs
- locking: use "raise LockTimeout from None" for prettier traceback
Co-authored-by: Thomas Portmann <thomas@portmann.org>
Co-authored-by: Thomas Waldmann <tw@waldmann-edv.de>
general.rst and man_intro.rst both included usage_general.rst.inc, which resulted in three Sphinx warning "WARNING: duplicate label".
To prevent this we move all sections of usage_general into own include files and add a second usage_general file without the three labels.
