<NME> rango.pre.gemspec
<BEF> #!/usr/bin/env gem build
# encoding: utf-8

# You might think this is a terrible mess and guess what, you're
# right mate! However say thanks to authors of RubyGems, not me.
eval(File.read("rango.gemspec")).tap do |specification|
  specification.version = "#{Rango::VERSION}.pre"
end

<MSG> Better pre gemspec

<DFF> @@ -4,5 +4,5 @@
 # You might think this is a terrible mess and guess what, you're
 # right mate! However say thanks to authors of RubyGems, not me.
 eval(File.read("rango.gemspec")).tap do |specification|
-  specification.version = "#{Rango::VERSION}.pre"
+  specification.version = "#{specification.version}.pre"
 end

Better pre gemspec