Fix running Subversion unit tests.
Review Request #12146 — Created March 14, 2022 and submitted
Recent changes to the test runner setup ended up causing Subversion unit
tests to fail to run. The
__test__ = Falseon the common test class
was respected, but carried through to the subclasses, preventing any
PySVN or Subvertpy tests from running.
__test__ = Trueon both subclasses, allowing them to run
Ran the Subversion unit tests. Verified they could now be run.