Merge branch 'fix_head_download_option' of https://github.com/neonichu/CocoaPods…

Merge branch 'fix_head_download_option' of https://github.com/neonichu/CocoaPods into neonichu-fix_head_download_option

Conflicts:
	spec/unit/installer/pod_source_installer_spec.rb

lib/cocoapods/installer/pod_source_installer.rb

@@ -63,7 +63,9 @@ module Pod
       def install!
         download_source unless predownloaded? || local?
         run_prepare_command
-      rescue => e
+      rescue Informative
+        raise
+      rescue Object => e
         UI.notice("Error installing #{root_spec.name}")
         clean!
         raise
@@ -99,8 +101,18 @@ module Pod
       def download_source
         root.rmtree if root.exist?
         if head_pod?
-          downloader.download_head
-          @specific_source = downloader.checkout_options
+          begin
+            downloader.download_head
+            @specific_source = downloader.checkout_options
+          rescue RuntimeError => e
+            if e.message == 'Abstract method'
+              raise Informative, "The pod '" + root_spec.name + "' does not " + 
+                "support the :head option, as it uses a " + downloader.name + 
+                " source. Remove that option to use this pod."
+            else
+              raise
+            end
+          end
         else
           downloader.download
           unless downloader.options_specific?

spec/unit/installer/pod_source_installer_spec.rb

@@ -81,6 +81,16 @@ module Pod
           partially_downloaded_file.should.not.exist
         end
 
+        it "fails when using :head for Http source" do
+          config.sandbox.store_head_pod('BananaLib')
+          @spec.source = { :http => 'http://dl.google.com/googleadmobadssdk/googleadmobsearchadssdkios.zip' }
+          @spec.source_files = 'GoogleAdMobSearchAdsSDK/*.h'
+          Pod::Downloader::Http.any_instance.stubs(:download_head)
+          should.raise Informative do
+            @installer.install!
+          end.message.should.match /does not support the :head option, as it uses a Http source./
+        end
+
       end
 
       #--------------------------------------#