[rubygems/rubygems] Fix resolver bug where ActivationRequest objects were not properly compared

They were delegating their `#hash` value to a class not overriding that
method, and so were returning inconsistent results.

https://github.com/rubygems/rubygems/commit/723e4ee0fc

lib/rubygems/resolver/spec_specification.rb

@@ -66,4 +66,11 @@ class Gem::Resolver::SpecSpecification < Gem::Resolver::Specification
   def version
     spec.version
   end
+
+  ##
+  # The hash value for this specification.
+
+  def hash
+    spec.hash
+  end
 end