This test was failing on my machine when run natively but not causing any
problems when run within qemu, and the failure was "mkdir: No space left
on device".
My understanding of the issue is that this test overflowed the temporary
disk image due to its high rate of file churn and the lfs_cleanerd not
being able to keep up. Note that this test is capped by time, not number
of operations, so this is why the problem does not show up in a slow
emulated system.
To fix this, just bump the test file system image limit a little bit.
(I tried increasing the frequency at which lfs_cleanerd does its thing,
but it wasn't enough.)
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