Simplify rescue catching

Rakefile

@@ -28,14 +28,8 @@ task :fetch_ace_modes do
   begin
     ace_github_modes = (open("https://api.github.com/repos/ajaxorg/ace/contents/lib/ace/mode").read)
     File.write(ACE_FIXTURE_PATH, ace_github_modes)
-  rescue => e
-    case e
-    when OpenURI::HTTPError
-    when SocketError
+  rescue OpenURI::HTTPError, SocketError
       # no internet? no problem.
-    else
-      raise e
-    end
   end
 end