SW-658: python3 adaptation: use cmp_to_key for new 'sorted' api

SAS/DataManagement/StorageQueryService/cache.py

@@ -11,6 +11,7 @@ import ast
 from optparse import OptionParser
 from threading import Thread, RLock
 import os.path
+from functools import cmp_to_key
 
 from lofar.messaging import EventMessage, ToBus
 from lofar.common.util import humanreadablesize
@@ -291,7 +292,7 @@ class CacheManager:
                             return 1
                         return 0
 
-                    updateable_entries = sorted(updateable_entries, cmp=compareFunc)
+                    updateable_entries = sorted(updateable_entries, key=cmp_to_key(compareFunc))
 
                     cacheUpdateStart = datetime.datetime.utcnow()