@tomduckering - adding a fix for the bug in the pessimistic constraint fixing for RPMs converted from Gems.
Fixes pessimistic constraint conversion

See jordansissel/fpm#693
Merged pull request: #693: Fix for bug in Gem pessimistic constraint conversion

See jordansissel/fpm#693 for more information

* pr/693:
  Fixes pessimistic constraint conversion
  @tomduckering - adding a fix for the bug in the pessimistic constraint fixing for RPMs converted from Gems.