Replace assert from Python testcases with code that always runs.

assert code is sometimes not executed, eg when running python -O.

Examples/test-suite/python/operbool_runme.py

@@ -1,3 +1,4 @@
 #!/usr/bin/env python
 import operbool
-assert not operbool.Test()
+if operbool.Test():
+    raise RuntimeError("operbool failed")