[Command::Spec] Fix computation of podspec path

CHANGELOG.md

@@ -15,6 +15,10 @@ To install or update CocoaPods see this [guide](http://docs.cocoapods.org/guides
   [#1106](https://github.com/CocoaPods/CocoaPods/issues/1106)  
   [#1045](https://github.com/CocoaPods/CocoaPods/issues/1045)  
 
+###### Bug Fixes
+
+* Fixed crash in `pod spec cat`.
+
 
 ## 0.23.0.rc1
 

lib/cocoapods/command/spec.rb

@@ -304,7 +304,7 @@ module Pod
       # @return [Pathname] the absolute path of the given spec and source
       #
       def pathname_from_spec(spec, source)
-        Pathname.new("~/.cocoapods/#{ source }/#{ spec.name }/#{ spec.version }/#{ spec.name }.podspec").expand_path
+        config.repos_dir + "#{source}/#{spec.name}/#{spec.version}/#{spec.name}.podspec"
       end
 
       # @return [String] of spec paths one on each line