The global blocks done to 89.204.128.0/19 (https://meta.wikimedia.org/wiki/Special:Log/?page=User:89.204.128.0/19) where not appropriately applied to the globalblocks table:
mysql:wikiadmin@db2068 [centralauth]> SELECT gb_address, gb_by, gb_reason, gb_timestamp FROM globalblocks WHERE gb_address = '89.204.128.0/19'; +-----------------+----------+----------------------------------------------------------------------------------------------------------------+----------------+ | gb_address | gb_by | gb_reason | gb_timestamp | +-----------------+----------+----------------------------------------------------------------------------------------------------------------+----------------+ | 89.204.128.0/19 | DerHexer | Long-term abuse of IP range; please contact stewards@wikimedia.org if you want us to create an account for you | 20170226211637 | +-----------------+----------+----------------------------------------------------------------------------------------------------------------+----------------+ 1 row in set (0.00 sec)
This lead to the blocks not being correctly enforced.
I skimmed the logs but I couldn't find anything relevant.