world: remove redundant hashing

This is probably a leftover from the memcached thing. There is no
need to hash a key to be used for hashmap access, as the hashmap
itself hashes it already, and probably with a hash more appropriate
for the situation.

overviewer_core/world.py

@@ -17,7 +17,6 @@ import functools
 import os
 import os.path
 import logging
-import hashlib
 import time
 import random
 import re
@@ -726,8 +725,6 @@ class CachedRegionSet(RegionSetWrapper):
 
         logging.debug("Initializing a cache with key '%s'", s)
 
-        s = hashlib.md5(s).hexdigest()
-
         self.key = s
 
     def get_chunk(self, x, z):