reuse debug option to run functional tests on foreground

Reuse the option "-D" to enable debug mode on funcional tests. This helps
to understand make API simpler.

product/ERP5Type/tests/ERP5TypeFunctionalTestCase.py

@@ -361,7 +361,8 @@ class ERP5TypeFunctionalTestCase(ERP5TypeTestCase):
     if self.remote_code_url_list is not None:
       self.runner.remote_code_url_list = self.remote_code_url_list
 
-    self.runner.test(debug=self.foreground)
+    debug = self.foreground or os.environ.get("erp5_debug_mode")
+    self.runner.test(debug=debug)
     detail, success, failure, error_title_list = self.runner.processResult()
 
     self.logMessage("-" * 79)

product/ERP5Type/tests/runUnitTest.py

@@ -661,6 +661,7 @@ def main(argument_list=None):
       sys.exit()
     elif opt == '-D':
       debug = 1
+      os.environ["erp5_debug_mode"] = str(debug)
     elif opt == "--coverage":
       if coverage:
         os.environ['coverage'] = arg