more careful reset_context for stored entity;

--- a/src/Pure/raw_simplifier.ML	Thu May 18 23:50:59 2023 +0200
+++ b/src/Pure/raw_simplifier.ML	Fri May 19 11:41:30 2023 +0200
@@ -722,7 +722,7 @@
   Simproc
    {name = name,
     lhss = map (Morphism.term phi) lhss,
-    proc = Morphism.transform phi proc,
+    proc = Morphism.transform phi proc |> Morphism.entity_reset_context,
     stamp = stamp};
 
 local