[Specification] Don't include the name of the preferred dependency in to_s.

This caused a Bug that lead to Pods with preferred dependencies to be always
installed.

Closes CocoaPods/Specs#464.

CHANGELOG.md

@@ -9,6 +9,9 @@
   [#489](https://github.com/CocoaPods/CocoaPods/issues/489)
 - CocoaPods now uses a recent version of Octokit.
   [#490](https://github.com/CocoaPods/CocoaPods/issues/490)
+- Fixed a bug that caused Pods with preferred dependencies to be always
+  installed.
+  [Specs#464](https://github.com/CocoaPods/CocoaPods/issues/464)
 
 ## 0.14.0.rc2
 

lib/cocoapods/local_pod.rb

@@ -95,10 +95,13 @@ module Pod
     end
 
     # @return [String] A string representation of the pod which indicates if
-    #                  the pods comes from a local source.
+    #                  the pods comes from a local source or has a preferred
+    #                  dependency.
     #
     def to_s
-      top_specification.to_s
+      s =  top_specification.to_s
+      s << " defaulting to #{top_specification.preferred_dependency} subspec" if top_specification.preferred_dependency
+      s
     end
 
     # @return [String] The name of the Pod.

lib/cocoapods/specification.rb

@@ -458,8 +458,7 @@ module Pod
     end
 
     def to_s
-      display_name = preferred_dependency.nil? ? name : "#{name}/#{preferred_dependency}"
-      "#{display_name} (#{version})"
+      "#{name} (#{version})"
     end
 
     def inspect