Message 368395 - Python tracker

The commit a1d9e0accd33af1d8e90fc48b34c13d7b07dcf57 introduced reference leaks:

$ ./python -m test -R 3:3 test__xxsubinterpreters -m test.test__xxsubinterpreters.RunFailedTests.test_traceback_propagated
(...)
test__xxsubinterpreters leaked [1863, 1861, 1863] references, sum=5587
test__xxsubinterpreters leaked [559, 558, 559] memory blocks, sum=1676
(...)