Follow code style and rename cs to m_cs in state repository (cc @AM5800)
Don't ban peer when we cannot process commits (follow-up #912)
When asking for commits, rely on the current tip instead of the best
known block header because there may be a gap of finalization states
between tip and best header. It fixes floating issue that has been discovered
in #906, thanks to not properly block_sync-ed nodes.
block_sync
-ed nodes.