runUnitTest: set HTTPRequest.retry_max_count

In case of ConflictError, request will be retied for
HTTPRequest.retry_max_count times. For Zope 2, the default value of the
class attribute was 3, but on Zope 4, default value is 0 and this is set
to 3 on startup (by Zope2.Startup.handlers.root_wsgi_handler).
This startup code is not executed by runUnitTest, we need to set
HTTPRequest.retry_max_count somewhere, otherwise ConflictError are not
retried during tests.

product/ERP5Type/tests/runUnitTest.py

@@ -546,6 +546,9 @@ def runUnitTestList(test_list, verbosity=1, debug=0, run_only=None):
   # Set debug mode after importing ZopeLite that resets it to 0
   cfg.debug_mode = debug
 
+  from ZPublisher.HTTPRequest import HTTPRequest
+  HTTPRequest.retry_max_count = 3
+
   from ZConfig.components.logger import handlers, logger, loghandler
   import logging
   root_logger = logging.getLogger()