diff --git a/lib/spack/spack/repo.py b/lib/spack/spack/repo.py
index 2d7ee3b3222..f16997e66df 100644
--- a/lib/spack/spack/repo.py
+++ b/lib/spack/spack/repo.py
@@ -1362,8 +1362,10 @@ def get_pkg_class(self, pkg_name):
         if not inspect.isclass(cls):
             tty.die("%s.%s is not a class" % (pkg_name, class_name))
 
-        new_cfg_settings = spack.config.get("packages").get(pkg_name, {}).get("package_attributes", {})
-        overidden_attrs = getattr(cls, 'overidden_attrs', {})
+        new_cfg_settings = (
+            spack.config.get("packages").get(pkg_name, {}).get("package_attributes", {})
+        )
+        overidden_attrs = getattr(cls, "overidden_attrs", {})
         for key, val in overidden_attrs.items():
             setattr(cls, key, val)
         # Keep track of every class attribute that is overidden by the config:
@@ -1374,7 +1376,7 @@ def get_pkg_class(self, pkg_name):
         for key, val in new_cfg_settings.items():
             new_overidden_attrs[key] = getattr(cls, key)
             setattr(cls, key, val)
-        setattr(cls, 'overidden_attrs', dict(new_overidden_attrs))
+        setattr(cls, "overidden_attrs", dict(new_overidden_attrs))
 
         return cls