https://issues.dlang.org/show_bug.cgi?id=13625
--- Comment #2 from Dicebot <pub...@dicebot.lv> --- It was discovered that deadlock issue was because of GDM bug. Updating it to 3.14.1 did take care of the problem (see also https://issues.dlang.org/show_bug.cgi?id=4890) Assertion still fires though. It looks like it only works in combined test suite because other threads happen to be created before this test is run. --