[issue31227] regrtest: reseed random with the same seed before running a test file

[STINNER Victor]

New submission from STINNER Victor:

Attached PR changes regrtest to reseed the random RNG before each test file. Use also more entropy for the seed: 2**32 (32 bits) rather than
10_000_000 (24 bits).

The change should avoid random failure of test_tools when hunting reference leaks: see bpo-31174.

Maybe it will also reduce false positive when hunting memory leaks, like bpo-31217.

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components: Tests
messages: 300438
nosy: haypo
priority: normal
severity: normal
status: open
title: regrtest: reseed random with the same seed before running a test file
versions: Python 2.7, Python 3.6, Python 3.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue31227>
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