move setattr back to get_pkg_class (since these config settings can affect class-level attrs)

lib/spack/spack/package_base.py

@@ -694,15 +694,6 @@ def __init__(self, spec):
 
         super(PackageBase, self).__init__()
 
-        # packages.yaml config can override package attributes. This is set
-        # on the instance rather than the class since the configuration can
-        # change between calls to repo.get for the same package.
-        settings = spack.config.get("packages").get(spec.name, {}).get("package_attributes", {})
-        for key, val in settings.items():
-            setattr(self, key, val)
-        # Note: the potential issue with setting these attributes here vs.
-        # in Repo.get is that subclasses could override these properties
-
     @classmethod
     def possible_dependencies(
         cls,

lib/spack/spack/repo.py

@@ -1362,6 +1362,16 @@ 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', {})
+        for key, val in overidden_attrs.items():
+            setattr(cls, key, val)
+        new_overidden_attrs = {}
+        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))
+
         return cls
 
     def __str__(self):