Fix race condition in Close()
Fix race condition in Close()

mailgun/sarama,HelixEducation/sarama,crast/sarama,Shopify/sarama,DataDog/sarama,HelixEducation/sarama,LastManStanding/sarama,Neuw84/sarama,rafrombrc/sarama,yangfan876/sarama,gyroscope-innovations/legacy_sarama,remerge/sarama,kraveio/sarama,betable/sarama,uovobw/sarama,Shopify/sarama,pronix/sarama,remerge/sarama,VividCortex/sarama,raisemarketplace/sarama,scalingdata/sarama,LastManStanding/sarama,raisemarketplace/sarama,vrischmann/sarama,vrischmann/sarama,winlinvip/sarama,betable/sarama,jepst/sarama,mailgun/sarama,jimmykuo/sarama,kraveio/sarama,uovobw/sarama,kmiku7/sarama,aybabtme/sarama,Neuw84/sarama,crast/sarama,cep21/sarama,gyroscope-innovations/legacy_sarama,winlinvip/sarama,scalingdata/sarama,jepst/sarama,aybabtme/sarama,kmiku7/sarama,rafrombrc/sarama,yangfan876/sarama,VividCortex/sarama,pronix/sarama,jimmykuo/sarama,cep21/sarama,DataDog/sarama