Re: [PATCH v2 2/2] update-index: refresh should rewrite index in case of racy timestamps

"Marc Strapetz via GitGitGadget" [off-list ref] writes:

+test_expect_success '--refresh has no racy timestamps to fix' '
+	reset_files &&
+	test-tool chmtime =1234567891 .git/index &&

Don't some people use Git on VFAT where the time resolution is 2
seconds?  1234567890 and 1234567891 differ only by one second, so
chmtime may not be able to store one of them exactly, so I am not
sure if this guarantees "no racy timestamps to fix".