Shane Becker - "Invalid gemspec in [/Users/s/.gem/ruby/1.9.3/specifications/ZenTest-4.9.2.gemspec]: Illformed requirement ["< 2.1, >= 1.8"]" Help?

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"Invalid gemspec in [/Users/s/.gem/ruby/1.9.3/specifications/ZenTest-4.9.2.gemspec]: Illformed requirement ["< 2.1, >= 1.8"]"

Help?