libgreen sched::test_spawn_sched_blocking is unstable

[chris-morgan]

Operating with a completely fresh build (git clean -fdx), the libgreen sched::test_spawn_sched_blocking test is sometimes hanging for me. (The other 24 tests in libgreen are successfully passing or being ignored, as appropriate.)

First of all I run make check and it hangs at that point. I kill it (^C) and try again and it passes.

$ rm -f tmp/check-stage2-T-x86_64-unknown-linux-gnu-H-x86_64-unknown-linux-gnu-green.ok
$ make check-stage2-green

And it hangs. Kill and retry the make check-stage2-green, and it passes.

As long as I rm -f the .ok file before running make check-stage2-green—whether or not that file exists—it fails, but if I then run make check-stage2-green again, it works again. The scary part is that this behaviour seems to be consistent, though that's ridiculous.

[alexcrichton]

This also appears to have failed on the linux bot recently: http://buildbot.rust-lang.org/builders/auto-linux-32-nopt-t/builds/2350/steps/test/logs/stdio