Pass on RhodeCode config file down to a python-based Hg hook via the extras pseudo-config key, see https://bitbucket.org/marcinkuzminski/rhodecode/issue/558/access-to-rhodecode-config-from-a-hg

rhodecode/lib/middleware/simplehg.py

@@ -152,12 +152,14 b' class SimpleHg(BaseVCSController):'
 
         # extras are injected into mercurial UI object and later available
         # in hg hooks executed by rhodecode
+        from rhodecode import CONFIG
         extras = {
             'ip': ipaddr,
             'username': username,
             'action': action,
             'repository': repo_name,
             'scm': 'hg',
+            'config': CONFIG['__file__'],
             'make_lock': None,
             'locked_by': [None, None]
         }