[Eva] Subdivision: do not forget to clear the valuation cache.

When the subdivision on a sub-expression [s] is performed according to [s] and
not according to the complete expression [e], we then reevaluate [e] with the
result of the subdivision. However, the valuation should be cleared before.
Otherwise, the reevaluation uses the cache and not the reduced values computed
by the subdivision.

src/plugins/value/engine/subdivided_evaluation.ml

@@ -787,6 +787,9 @@ module Make
                  instead of [expr]. Use [~expr:subexpr], then evaluate [expr]
                  with the reduced valuation, then continue to subdivide. *)
               subdivide ~expr:subexpr ~subexpr >>> fun valuation _ _ ->
+              let valuation =
+                Clear.clear_englobing_exprs valuation ~expr ~subexpr
+              in
               Eva.evaluate context valuation expr >>>
               subdivide_subexpr tail
       in