# Delete any stale cache.
stale_hashes = cached_hashes.difference(valid_pkg_hashes)
if stale_hashes:
- for base_name_hash, bucket in base_names.items():
+ for base_name_hash, bucket in list(base_names.items()):
for hash_value in stale_hashes.intersection(bucket):
del bucket[hash_value]
if not bucket: