[issue35879] test_type_comments leaks references

[STINNER Victor]

New submission from STINNER Victor <vstinner at redhat.com>:

https://buildbot.python.org/all/#/builders/1/builds/490

https://buildbot.python.org/all/#/builders/80/builds/499

test_type_comments leaked [37, 37, 37] references, sum=111
test_type_comments leaked [11, 12, 11] memory blocks, sum=34

Example:

vstinner at apu$ ./python -m test -R 3:3 test_type_comments -m test.test_type_comments.TypeCommentTests.test_asyncdef
Run tests sequentially
0:00:00 load avg: 0.56 [1/1] test_type_comments
beginning 6 repetitions
123456
......
test_type_comments leaked [2, 2, 2] references, sum=6
test_type_comments leaked [2, 3, 2] memory blocks, sum=7
test_type_comments failed

== Tests result: FAILURE ==

1 test failed:
    test_type_comments

Total duration: 129 ms
Tests result: FAILURE


I bet that the regression comes from:

commit dcfcd146f8e6fc5c2fc16a4c192a0c5f5ca8c53c
Author: Guido van Rossum <guido at python.org>
Date:   Thu Jan 31 03:40:27 2019 -0800

    bpo-35766: Merge typed_ast back into CPython (GH-11645)


See also bpo-35878.

----------
components: Library (Lib)
messages: 334671
nosy: lukasz.langa, vstinner
priority: normal
severity: normal
status: open
title: test_type_comments leaks references
versions: Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue35879>
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