Fix script/generate warning

railties/lib/rails_generator/lookup.rb

@@ -208,7 +208,8 @@ def initialize
     class GemGeneratorSource < AbstractGemSource
       # Yield latest versions of generator gems.
       def each
-        Gem::cache.search(/_generator$/).inject({}) { |latest, gem|
+        dependency = Gem::Dependency.new(/_generator$/, Gem::Requirement.default)
+        Gem::cache.search(dependency).inject({}) { |latest, gem|
           hem = latest[gem.name]
           latest[gem.name] = gem if hem.nil? or gem.version > hem.version
           latest