Skip some tests if extracted from tarball (again)

Fix up previous commit

ref
9aa75795f9f438d5c874d8e418c3c7cdd63024fa,
38002a8adbd98266426940d829429a30af0622a4, and
0e60b59d5884edb8f9aea023efd9b24f1ff02049

spec/bundler/support/helpers.rb

@@ -576,5 +576,11 @@ module Spec
       end
       port
     end
+
+  private
+
+    def git_root_dir?
+      root.to_s == `git rev-parse --show-toplevel`.chomp
+    end
   end
 end