Fix issues running Perforce unit tests.
Fix issues running Perforce unit tests.

The Perforce test suite had two issues have have cropped up. First, if
the local computer's hostname was in the form of `MyComputer.tld`
instead of `MyComputer`, a comparison would fail. We were comparing the
entire string when we should have just compared the first part.

Second, the `anonymous` user we were using for
`public.perforce.com:1666` could no longer be used. Instead, they have a
`guest` user, which functions like `anonymous` once did. We now use this
for our tests instead.

Testing Done:
Unit tests pass.

Reviewed at https://reviews.reviewboard.org/r/10350/

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