scipy/scipy — pull request #4294 by argriffing (2014-12-18 23:38:36+00:00)
Title: MAINT: pchanial's improvement of input validation in sparse's __mul__

Retry of @pchanial's https://github.com/scipy/scipy/pull/4066, this time with tests and in its own PR branch. Also changed `raise NotImplemented` to `raise NotImplementedError`.