Strange NFS file issue affecting sstate test

[Richard Purdie <richard.purdie@linuxfoundation.org>]

In this commit we removed some checks on the basis we wanted to better
understand them:

https://git.yoctoproject.org/poky/commit/?id=4675bbb757a4755e80914afb6840a640f292fc08

We ran into the file not found issue in this build:

https://autobuilder.yoctoproject.org/typhoon/#/builders/87/builds/6337/steps/14/logs/stdio

Logging onto the worker in question (ubuntu2304-ty-1) just showed a "?"
against the file in a directory listing and no content. There was
metadata but nothing behind it. The timestamps were showing epoch dates
(0).

The file was:

/srv/autobuilder/autobuilder.yocto.io/pub/sstate/universal/61/8a/sstate:pigz-native:x86_64-linux:2.8:r0:x86_64:11:618a4ce721368d70eb1112081db1b54f9a4e3ffb4b593a7c994ad9bb38901dea_configure.tar.zst.siginfo

which is on the autobuilder NAS over NFS.

It did not list as present on any other worker. I also noticed it was
the only file in that directory on that worker and on other workers
there was a different file present.

I think if I understand Michael correctly, creating another file in the
directory seemed to refresh the directory, the bad entry disappeared
and normal service resumed.

To learn more we'll probably need to see it happen again and to let
Michael know when it does. I'm writing this down so we have a record of
what we know so far.

Cheers,

Richard