scalaz/scalaz — comment on commit d71abed072f271dbcecd159d3fdaac516e49ebb6
File:  line 0
By retronym:

I read Oleg's response to mean that while full set of laws is not agreed, `m >> mzero = mzero` is commonly accepted.

We can resurrect the instance with a warning in the documentation and test; perhaps that warning can be echoed on `PlusEmpty` itself.