Use start and stop methods of patch in scenario

This ensure that the modification on the object are removed at the end of the
scenario.

issue10422
review332891002

trytond/tests/test_tryton.py

@@ -901,6 +901,7 @@ def doctest_setup(test):
 
 
 def doctest_teardown(test):
+    unittest.mock.patch.stopall()
     return drop_db()