Log the value which is observed in the first place.

The name 'result' is of bool type and has no len property,
resulting in a TypeError. Futhermore in the flow control
conn.response is observed and hence should be reported.

Signed-off-by: Daniel Ehlers <sargon@toppoint.de>

synapse/handlers/auth.py

@@ -660,7 +660,7 @@ class AuthHandler(BaseHandler):
                 else:
                     logger.warn(
                         "ldap registration failed: unexpected (%d!=1) amount of results",
-                        len(result)
+                        len(conn.response)
                     )
                     defer.returnValue(False)