Don't GC if in atomic mode(have temporarily switched to master)

src/racket/src/thread.c

@@ -4234,7 +4234,8 @@ void scheme_thread_block(float sleep_time)
 
   /* Check for major GC request from master GC */
 #if defined(MZ_PRECISE_GC) && defined(MZ_USE_PLACES)
-  GC_check_master_gc_request(); 
+  if (!do_atomic)
+    GC_check_master_gc_request(); 
 #endif
   
   if (sleep_end > 0) {