D-Programming-Language/dmd — pull request #3913 by yebblies (2014-08-28 15:38:23+00:00)
Title: Remove special handling of `delete aa[key]`.

This has been an error for a couple of years, and has been deprecated since pre D 1.0.

I couldn't find a bugzilla report as (I'm guessing) the deprecation predates bugzilla.