[phobos] [D-Programming-Language/phobos] 2742d9: Remove isExactSomeString in std.conv

[GitHub]

  Branch: refs/heads/convIsSomeString
  Home:   https://github.com/D-Programming-Language/phobos
  Commit: 2742d94be9eeb8cfd6c572a470fe5fb653151772
      https://github.com/D-Programming-Language/phobos/commit/2742d94be9eeb8cfd6c572a470fe5fb653151772
  Author: monarch dodra <monarchdodra at gmail.com>
  Date:   2013-09-16 (Mon, 16 Sep 2013)

  Changed paths:
    M std/conv.d

  Log Message:
  -----------
  Remove isExactSomeString in std.conv

Since now that's the default behavior of `isSomeString` anyways.