Delay the free_vararg_length check within intersect_var

We should not skip the `check_unsat_bound`.

Co-Authored-By: Jameson Nash <vtjnash+github@gmail.com>

Author: N5N3

src/subtype.c

@@ -2366,10 +2366,6 @@ static jl_value_t *intersect_var(jl_tvar_t *b, jl_value_t *a, jl_stenv_t *e, int
                 ub = (jl_value_t*)b;
             }
         }
-        if (has_free_vararg_length(ub, e) && !has_free_vararg_length(a, e)) {
-            bb->ub = ub;
-            ub = (jl_value_t*)b;
-        }
         if (ub != (jl_value_t*)b) {
             if (jl_has_free_typevars(ub)) {
                 if (check_unsat_bound(ub, b, e)) {
@@ -2378,6 +2374,11 @@ static jl_value_t *intersect_var(jl_tvar_t *b, jl_value_t *a, jl_stenv_t *e, int
                 }
             }
             bb->ub = ub;
+            // We get a imprecise Tuple here. Don't change `lb` and return the typevar directly. 
+            if (has_free_vararg_length(ub, e) && !has_free_vararg_length(a, e)) {
+                JL_GC_POP();
+                return (jl_value_t*)b;
+            }
             bb->lb = ub;
         }
         JL_GC_POP();