testCMFActivity: Do not hide actual failure cause.

The main change here is the reduction of try..except scope, so failing the
first assertion does not cause an AttributeError about original_query.
Also, avoid code duplication by just checking final number of messages
outside the try..except block.
Also, improve coding style (spaces around operators and commas).
Also, avoid single-use variable.
Also, fix typo in comment.

product/CMFActivity/tests/testCMFActivity.py

@@ -45,6 +45,8 @@ from zLOG import LOG
 from ZODB.POSException import ConflictError
 from DateTime import DateTime
 from Products.CMFActivity.ActivityTool import Message
+from _mysql_exceptions import OperationalError
+from Products.ZMySQLDA.db import DB
 import gc
 import random
 import threading
@@ -616,37 +618,31 @@ class TestCMFActivity(ERP5TypeTestCase, LogInterceptor):
       organisation_module.newContent(id=self.company_id)
     o = organisation_module._getOb(self.company_id)
     self.commit()
-    self.flushAllActivities(silent = 1, loop_size = 10)
+    self.flushAllActivities(silent=1, loop_size=10)
     self.assertEqual(len(activity_tool.getMessageList()), 0)
 
-    from _mysql_exceptions import OperationalError
-
     # Monkey patch Queue to induce conflict errors artificially.
     def query(self, query_string,*args, **kw):
-      # No so nice, this is specific to zsql method
-      if query_string.find("REPLACE INTO")>=0:
+      # Not so nice, this is specific to zsql method
+      if "REPLACE INTO" in query_string:
         raise OperationalError
-      else:
       return self.original_query(query_string,*args, **kw)
-    from Products.ZMySQLDA.db import DB
     portal = self.getPortal()
 
-    try:
     # Test some range of conflict error occurences.
     organisation_module.recursiveReindexObject()
     self.commit()
-      self.assertEqual(len(activity_tool.getMessageList()), 1)
+    self.assertTrue(len(activity_tool.getMessageList()), 1)
+    try:
       DB.original_query = DB.query
       DB.query = query
       portal.portal_activities.distribute()
       portal.portal_activities.tic()
       self.commit()
-      DB.query = DB.original_query
-      message_list = portal.portal_activities.getMessageList()
-      self.assertEqual(len(message_list),1)
     finally:
       DB.query = DB.original_query
       del DB.original_query
+    self.assertEqual(len(portal.portal_activities.getMessageList()), 1)
 
   def checkIsMessageRegisteredMethod(self, activity):
     activity_tool = self.getPortal().portal_activities