We no longer have a .release task
Update lib/elixir/lib/hash_dict.ex

Update comments
Preserving mtime needs to be invoked per task
Revert "Merge pull request #778 from alexrp/master"

There is still some discussion pending on this, see #791

This reverts commit f2d4d1e0b9d11fbcca000e9a9d4e33c0d98ee079, reversing
changes made to c524bcdeb2271ce08872cbffb18549844024eaa5.