=> Bootstrap dependency digest>=20010302: found digest-20180917
===> Building for ruby25-rack16-1.6.11
=> Override gemspec dependency
rackup => rackup16
bin/rackup => bin/rackup16
=> Removing backup files of patch before build
WARNING:  bin/rackup16 is not executable
WARNING:  See http://guides.rubygems.org/specification-reference/ for help
  Successfully built RubyGem
  Name: rack
  Version: 1.6.11
  File: rack-1.6.11.gem