fix order of setting Task result and state

Author: JeffBezanson

src/task.c

@@ -151,14 +151,14 @@ void JL_NORETURN jl_finish_task(jl_task_t *t, jl_value_t *resultval JL_MAYBE_UNR
 {
     jl_ptls_t ptls = jl_get_ptls_states();
     JL_SIGATOMIC_BEGIN();
+    t->result = resultval;
+    jl_gc_wb(t, t->result);
     if (t->exception != jl_nothing)
-        t->state = failed_sym;
+        jl_atomic_store_release(&t->state, failed_sym);
     else
-        t->state = done_sym;
+        jl_atomic_store_release(&t->state, done_sym);
     if (t->copy_stack) // early free of stkbuf
         t->stkbuf = NULL;
-    t->result = resultval;
-    jl_gc_wb(t, t->result);
     // ensure that state is cleared
     ptls->in_finalizer = 0;
     ptls->in_pure_callback = 0;