Do not boot on flush

app/boot.py

@@ -26,7 +26,7 @@ from webodm.wsgi import booted
 def boot():
     # booted is a shared memory variable to keep track of boot status
     # as multiple gunicorn workers could trigger the boot sequence twice
-    if (not settings.DEBUG and booted.value) or settings.MIGRATING: return
+    if (not settings.DEBUG and booted.value) or settings.MIGRATING or settings.FLUSHING: return
 
     booted.value = True
     logger = logging.getLogger('app.logger')