Fix isparameter to work in old case

Author: shashi

src/parameters.jl

@@ -3,7 +3,14 @@ struct MTKParameterCtx end
 
 function isparameter(x)
     x = unwrap(x)
-    if istree(x) && operation(x) isa Symbolic
+
+    #TODO: Delete this branch
+    if x isa Symbolic && Symbolics.getparent(x, false) !== false
+        p = Symbolics.getparent(x)
+        isparameter(p) ||
+        (hasmetadata(p, Symbolics.VariableSource) &&
+         getmetadata(p, Symbolics.VariableSource)[1] == :parameters)
+    elseif istree(x) && operation(x) isa Symbolic
         getmetadata(x, MTKParameterCtx, false) ||
             isparameter(operation(x))
     elseif istree(x) && operation(x) == (getindex)