allow index.TestCase to work when run using any path

tests/index.TestCase

@@ -1,9 +1,18 @@
 #!/usr/bin/env python3
+
+import inspect
 import optparse
 import os
+import sys
 import unittest
 import zipfile
 
+localmodule = os.path.realpath(
+    os.path.join(os.path.dirname(inspect.getfile(inspect.currentframe())), '..'))
+print('localmodule: ' + localmodule)
+if localmodule not in sys.path:
+    sys.path.insert(0, localmodule)
+
 import fdroidserver.common
 import fdroidserver.index
 import fdroidserver.signindex