All servers are eagerly flushed at the end of a multi block

[naveg]

This is a known issue, described in the original pull: #844

Here is a proof of concept for how this might be improved, by defering the flushing of responses to the next non-multi command on a per-server basis: braze-inc@58fedb2

This is written against Dalli 2.x, but the same idea could apply to Dalli 3.x