Fixes saltstack#34043

saltstack#34206)

The work I need to do in the loader to achieve this is not likely to be
done in time for the Carbon release.

Handle child PIDs differently depending on the availability of psutils

* Add salt.utils.is_hex()

* dulwich: use salt.utils.is_hex() to confirm ref is hexidecimal

* Restore ability for SHA1 saltenvs to be used in gitfs

This uses salt.utils.is_hex() to check if the desired environment is
hex, and allowing it to be used for gitfs operations when it is.

* pygit2: Catch ValueError when trying to resolve SHA1

Hex SHAs which are less than 4 characters will raise a ValueError, this
commit catches these exceptions.

See saltstack#34213 for more information.

… objects via s3.query to fail (saltstack#34208)

No conflicts.