gem.add_dependency "this_gem", ">= 2.0.1.pre.joe.2", "< 2.0.2"

rake aborted!
Bundler::GemspecError:
[!] There was an error while loading `foo.gemspec`: Illformed requirement ["=> 2.0.1.pre.joe.2"]. Bundler cannot continue.

 #  from /home/user/src/dep_project/gem/foo.gemspec:34
 #  -------------------------------------------
 #
 >    spec.add_dependency "this_gem", "=> 2.0.1.pre.joe.2", "< 2.0.2"
 #    spec.add_dependency "json", ">= 2.0.0"
 #  -------------------------------------------