test_futimens is flaky on ARM64 macOS. #25280
Description
on Apple Silicon macOS M1, the core test test_futimens (in both parameters test_futimens_nodefs and test_futimens_rawfs) fails occassionally, e.g.
thinlto0.test_futimens_rawfs
llvmlibc.test_futimens_rawfs
corez.test_futimens_rawfs
thinlto1.test_futimens_nodefs
ltoz.test_futimens_nodefs
core2ss.test_futimens_nodefs
ltos.test_futimens_rawfs
with a timestamp difference.
Reading the code, I am not quite able to find what could cause such a timestamp divergence. There does not seem to be room for such behavior as far as I could tell.
The test is not flaky on any other bots that I run (Windows or Linux). Specifically, it is not flaky on my macOS x64 bot either, only on macOS M1 bot.