hack in a fix to getting the right lambda for the incremental deserializer

fix #18449
(the real, non-buggy fix is in #18413 for v0.6-dev master)

Author: vtjnash

src/gf.c

@@ -122,7 +122,7 @@ JL_DLLEXPORT jl_lambda_info_t *jl_specializations_get_linfo(jl_method_t *m, jl_t
 {
     JL_LOCK(&m->writelock);
     jl_typemap_entry_t *sf = jl_typemap_assoc_by_type(m->specializations, type, NULL, 1, /*subtype*/0, /*offs*/0);
-    if (sf && jl_is_lambda_info(sf->func.value) && ((jl_lambda_info_t*)sf->func.value)->code != jl_nothing) {
+    if (sf && jl_is_lambda_info(sf->func.value) && (!allow_exec || sf->func.linfo->code != jl_nothing)) {
         JL_UNLOCK(&m->writelock);
         return (jl_lambda_info_t*)sf->func.value;
     }