Index: svn_authz.py
===================================================================
--- svn_authz.py	(revision 4326)
+++ svn_authz.py	(working copy)
@@ -31,6 +31,8 @@
     authz_module_name = Option('trac', 'authz_module_name', '',
         """The module prefix used in the authz_file.""")
 
+    authz_username_map = Option('trac', 'authz_username_map', '',
+        """Path to a username map to translate authname into svn accounts.""")
 
 def SubversionAuthorizer(env, repos, authname):
     authz_file = env.config.get('trac', 'authz_file')
@@ -38,8 +40,17 @@
         return Authorizer()
 
     module_name = env.config.get('trac', 'authz_module_name')
-    return RealSubversionAuthorizer(repos, authname, module_name, authz_file)
+    map_file = env.config.get('trac', 'authz_username_map')
+    if map_file:
+        from ConfigParser import ConfigParser
+        authz_map = ConfigParser()
+        authz_map.read(map_file)
 
+        if authz_map.has_option('users', authname):
+            authname = authz_map.get('users', authname)
+
+    return RealSubversionAuthorizer(repos, authname, module_name, authz_file, None)
+
 def parent_iter(path):
     path = path.strip('/')
     if path: