Spurious failure in test_inherit_env #55503
Description
Symptom: the test process::tests::test_inherit_env failed even if the PR doesn't touch this part of the standard library.
[01:56:52] test process::tests::test_inherit_env ... FAILED
...
[01:56:52] thread '<unnamed>' panicked at 'output doesn't contain `RUN_TEST_NEW_ENV2=456`
...
Previous instances:
- 2018-10-30T10:42:14Z: Update clippy #55496 (comment) (arm-android)
- 2018-09-08T08:22:09Z: Update Cargo and RLS #53935 (comment) (x86_64-gnu-distcheck)
It is known that this test had a race condition, and the fix #42795 wasn't merged.