Fix memory leak caused by using rabbit as the result backend for celery
Fix memory leak caused by using rabbit as the result backend for celery

felliott/scrapi,jeffreyliu3230/scrapi,erinspace/scrapi,icereval/scrapi,mehanig/scrapi,fabianvf/scrapi,mehanig/scrapi,alexgarciac/scrapi,CenterForOpenScience/scrapi,CenterForOpenScience/scrapi,ostwald/scrapi,felliott/scrapi,fabianvf/scrapi,erinspace/scrapi