fix __file__ issue in python 3.8 tests

supvisors/tests/base.py

@@ -19,6 +19,7 @@
 
 import os
 import random
+import supvisors
 
 from socket import gethostname
 from unittest.mock import Mock
@@ -190,9 +191,8 @@ class DummyHttpContext:
     """ Simple HTTP context for web ui views. """
 
     def __init__(self, template=None):
-        import supvisors
-        module_path = os.path.dirname(supvisors.__file__)
-        self.template = os.path.join(module_path, template) if template else None
+        supvisors_path = next(iter(supvisors.__path__), '.')
+        self.template = os.path.join(supvisors_path, template) if template else None
         self.supervisord = DummySupervisor()
         # create form and response
         self.form = {'SERVER_URL': 'http://10.0.0.1:7777',