[Resolver] Allow LazySpecs to stay unrealized for longer

lib/cocoapods/resolver.rb

@@ -16,7 +16,7 @@ end
 module Pod
 
   class Specification::Set
-    class LazySpecification
+    class LazySpecification < BasicObject
       attr_reader :name, :version, :source
 
       def initialize(name, version, source)
@@ -29,6 +29,14 @@ module Pod
         specification.send(method, *args, &block)
       end
 
+      def subspec_by_name(name = nil)
+        if !name || name == self.name
+          self
+        else
+          specification.subspec_by_name(name)
+        end
+      end
+
       def specification
         @specification ||= source.specification(name, version)
       end