Remove vestigial variants in directory name.

lib/spack/spack/directory_layout.py

@@ -198,14 +198,10 @@ def hidden_file_paths(self):
 
     def relative_path_for_spec(self, spec):
         _check_concrete(spec)
-        
+
         if spec.external:
             return spec.external
 
-        enabled_variants = (
-            '-' + v.name for v in spec.variants.values()
-            if v.enabled)
-
         dir_name = "%s-%s-%s" % (
             spec.name,
             spec.version,