Believe this was caused by #898 https://github.com/weaveworks/cortex/commit/5c03d254dd4bae6aeebee481ae635d9d7026d8cf#diff-d7122b828e5806f5da647427488f01f1R362 plus this: https://github.com/weaveworks/cortex/commit/075c22fd401664cd79f86c512ec49e0dc504e044#diff-e39b4d67019ef4238a6408e2aabe4725R248