old_contents: ##############################################################################
  # Copyright (c) 2013-2016, Lawrence Livermore National Security, LLC.
  # Produced at the Lawrence Livermore National Laboratory.
  #
  # This file is part of Spack.
  # Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
  # LLNL-CODE-647188
  #
  # For details, see https://github.com/llnl/spack
  # Please also see the LICENSE file for our notice and the LGPL.
  #
  # This program is free software; you can redistribute it and/or modify
  # it under the terms of the GNU Lesser General Public License (as
  # published by the Free Software Foundation) version 2.1, February 1999.
  #
  # This program is distributed in the hope that it will be useful, but
  # WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
  # conditions of the GNU Lesser General Public License for more details.
  #
  # You should have received a copy of the GNU Lesser General Public
  # License along with this program; if not, write to the Free Software
  # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  ##############################################################################
  from spack import *
  
  
  class Ghostscript(Package):
      """An interpreter for the PostScript language and for PDF."""
  
      homepage = "http://ghostscript.com/"
      url = "http://downloads.ghostscript.com/public/old-gs-releases/ghostscript-9.18.tar.gz"
  
      version('9.18', '33a47567d7a591c00a253caddd12a88a')
  
      parallel = False
  
      depends_on('libtiff')
  
      def install(self, spec, prefix):
          configure('--prefix={0}'.format(prefix),
                    '--with-system-libtiff')
  
          make()
          make('install')
  
new_contents: ##############################################################################
  # Copyright (c) 2013-2016, Lawrence Livermore National Security, LLC.
  # Produced at the Lawrence Livermore National Laboratory.
  #
  # This file is part of Spack.
  # Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
  # LLNL-CODE-647188
  #
  # For details, see https://github.com/llnl/spack
  # Please also see the LICENSE file for our notice and the LGPL.
  #
  # This program is free software; you can redistribute it and/or modify
  # it under the terms of the GNU Lesser General Public License (as
  # published by the Free Software Foundation) version 2.1, February 1999.
  #
  # This program is distributed in the hope that it will be useful, but
  # WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
  # conditions of the GNU Lesser General Public License for more details.
  #
  # You should have received a copy of the GNU Lesser General Public
  # License along with this program; if not, write to the Free Software
  # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  ##############################################################################
  from spack import *
  
  
  class Ghostscript(Package):
      """An interpreter for the PostScript language and for PDF."""
  
      homepage = "http://ghostscript.com/"
      url = "https://github.com/ArtifexSoftware/ghostpdl-downloads/releases/download/gs921/ghostscript-9.21.tar.gz"
  
      version('9.21', '6f60d7fcb5eef6a8bec5abedf21c6a7008a8c0c7')
      version('9.18', '33a47567d7a591c00a253caddd12a88a')
  
      parallel = False
  
      depends_on('libtiff')
  
      def url_for_version(self, version):
          baseurl = "https://github.com/ArtifexSoftware/ghostpdl-downloads/releases/download/gs{0}/ghostscript-{1}.tar.gz"
          return baseurl.format(version.joined, version.dotted)
  
      def install(self, spec, prefix):
          configure('--prefix={0}'.format(prefix),
                    '--with-system-libtiff')
  
          make()
          make('install')
  
subject: add version 9.21 and handle new URL format (#3898)