[phobos] [dlang/phobos] bde976: use covariant tests rather than exact ones

[GitHub via phobos]

  Branch: refs/heads/master
  Home:   https://github.com/dlang/phobos
  Commit: bde976683e4c11578ccd8c8d180e8f1fc2da1f4a
      https://github.com/dlang/phobos/commit/bde976683e4c11578ccd8c8d180e8f1fc2da1f4a
  Author: Walter Bright <walter at walterbright.com>
  Date:   2016-06-24 (Fri, 24 Jun 2016)

  Changed paths:
    M std/functional.d

  Log Message:
  -----------
  use covariant tests rather than exact ones


  Commit: 643d42b28d3168790946cbd91dbc72e8162d64d4
      https://github.com/dlang/phobos/commit/643d42b28d3168790946cbd91dbc72e8162d64d4
  Author: Andrei Alexandrescu <andrei at erdani.com>
  Date:   2016-06-25 (Sat, 25 Jun 2016)

  Changed paths:
    M std/functional.d

  Log Message:
  -----------
  Merge pull request #4461 from WalterBright/cov-functional

use covariant tests rather than exact ones


Compare: https://github.com/dlang/phobos/compare/d42eff4ff877...643d42b28d31