Being a random test, this doesn't always trip. Happened in the autotester on Win32 platform.
Comment #1 by bugzilla — 2014-12-11T00:42:52Z
The failing test was introduced by WebDrake on Aug 21, 2013.
Comment #2 by dlang-bot — 2019-12-03T10:47:22Z
@berni44 created dlang/phobos pull request #7299 "Fix Issue 13853 - Assert fail in std.random unittests" fixing this issue:
- Fix Issue 13853 - Assert fail in std.random unittests:
std\random.d(2890): 99: 5323 > 5300
https://github.com/dlang/phobos/pull/7299
Comment #3 by bugzilla — 2020-01-02T14:50:56Z
Seems like there is some acceptance in the community of tests which nearly always succeed. For the test here the probability of failing erroneously is less than 1:10000.