* bpo-26732: fix too many fds in processes started with the "forkserver" method
A child process would inherit as many fds as the number of still-running children.
* Add blurb and test comment
* Change the regrtest --huntrleaks checker to decide if a test file
leaks or not. Require that each run leaks at least 1 reference.
* Warmup runs are now completely ignored: ignored in the checker test
and not used anymore to compute the sum.
* Add an unit test for a reference leak.
Example of reference differences previously considered a failure
(leak) and now considered as success (success, no leak):
[3, 0, 0]
[0, 1, 0]
[8, -8, 1]
* Fix "-m test --forever": replace _test_forever() with self._test_forever()
* Add unit test for --forever
* Add unit test for a failing test
* Fix also some pyflakes warnings in libregrtest
Antoine Pitrou
Victor Stinner
Ivan Levkivskyi
Serhiy Storchaka