origin: Switch baserefspec → refspec when de-layering

The idea originally was that we'd switch to `baserefspec` when
performing changes such that `ostree admin upgrade` would no longer
work.  But that has long since been buggy since the introduction
of things like `rpm-ostree initramfs --enable` etc.

The only goal of this PR is to avoid "leaking state" across
origin switches, so that the work to map origin ⇔ treefile
can also (correctly) be stateless.

src/libpriv/rpmostree-origin.cxx

@@ -566,17 +566,15 @@ update_keyfile_pkgs_from_cache (RpmOstreeOrigin *origin,
 
   if (g_hash_table_size (pkgs) > 0)
     {
-      switch (origin->refspec_type)
-        {
-        case RPMOSTREE_REFSPEC_TYPE_OSTREE:
-        case RPMOSTREE_REFSPEC_TYPE_CHECKSUM:
-          {
-            g_key_file_set_value (origin->kf, "origin", "baserefspec",
-                                  origin->cached_refspec);
-            g_key_file_remove_key (origin->kf, "origin", "refspec", NULL);
-            break;
-          }
-        }
+      g_key_file_set_value (origin->kf, "origin", "baserefspec",
+                            origin->cached_refspec);
+      g_key_file_remove_key (origin->kf, "origin", "refspec", NULL);
+    }
+  else
+    {
+      g_key_file_set_value (origin->kf, "origin", "refspec",
+                            origin->cached_refspec);
+      g_key_file_remove_key (origin->kf, "origin", "baserefspec", NULL);
     }
 }