[REF] has_test_errors: Detect error if there is a traceback in the log

Fix OCA#600

travis/test_server.py

@@ -33,6 +33,7 @@ def has_test_errors(fname, dbname, odoo_version, check_loaded=True):
         ]
     errors_report = [
         lambda x: x['loglevel'] == 'CRITICAL',
+        '\nTraceback \(most recent call last\):\n',
         'At least one test failed',
         'no access rules, consider adding one',
         'invalid module names, ignored',