Fix a potential race in rpc.Server shutdown.
Fix a potential race in rpc.Server shutdown.

I suspect that a connection is arriving after s.Close has been called,
so it needs to be closed in the ConnState hook instead of in s.Close.

Fixes #1444.

freakynit/cockroach,Abioy/cockroach,ajayaa/cockroach,chrisseto/cockroach,mbonaci/cockroach,Abioy/cockroach,GokulSrinivas/cockroach,sunya123/cockroach,ajayaa/cockroach,cuongdo/cockroach,jess-edwards/cockroach,mbonaci/cockroach,XisiHuang/cockroach,cockroachdb/cockroach,alunarbeach/cockroach,vivekmenezes/cockroach,jamesgraves/cockroach,vivekmenezes/cockroach,sunya123/cockroach,chrisseto/cockroach,maxlang/cockroach,il9ue/cockroach,arypurnomoz/cockroach,XisiHuang/cockroach,yosiat/cockroach,loucash/cockroach,il9ue/cockroach,jamesgraves/cockroach,abhishekgahlot/cockroach,Abioy/cockroach,chrisseto/cockroach,maxlang/cockroach,bg451/cockroach,yiixiansheng/cockroach,yiixiansheng/cockroach,hassyma/cockroach,arjun4084346/cockroach,mbertschler/cockroach,vivekmenezes/cockroach,briceburg/cockroach,slavau/cockroach,sunya123/cockroach,il9ue/cockroach,fengshao0907/cockroach,briceburg/cockroach,yosiat/cockroach,loucash/cockroach,alex/cockroach,mbertschler/cockroach,jmank88/cockroach,cuongdo/cockroach,nieyy/cockroach,cockroachdb/cockroach,vaibhavarora/cockroach,SustainFund/cockroach,SustainFund/cockroach,GokulSrinivas/cockroach,nkhuyu/cockroach,veteranlu/cockroach,sunya123/cockroach,XisiHuang/cockroach,maxlang/cockroach,abhishekgahlot/cockroach,linearb/cockroach,vivekmenezes/cockroach,petermattis/cockroach,arjun4084346/cockroach,cockroachdb/cockroach,sunya123/cockroach,ajayaa/cockroach,vaibhavarora/cockroach,c4pt0r/cockroach,vaibhavarora/cockroach,bg451/cockroach,cockroachdb/cockroach,yiixiansheng/cockroach,abhishekgahlot/cockroach,jmank88/cockroach,Abioy/cockroach,petermattis/cockroach,fengshao0907/cockroach,yosiat/cockroach,chrisseto/cockroach,c4pt0r/cockroach,ajayaa/cockroach,arjun4084346/cockroach,abhishekgahlot/cockroach,marcuswestin/cockroach,XisiHuang/cockroach,jamesgraves/cockroach,petermattis/cockroach,jgautheron/cockroach,slavau/cockroach,slavau/cockroach,jmank88/cockroach,paperstreet/cockroach,GokulSrinivas/cockroach,maxlang/cockroach,nieyy/cockroach,vivekmenezes/cockroach,nkhuyu/cockroach,paperstreet/cockroach,mbonaci/cockroach,arypurnomoz/cockroach,marcuswestin/cockroach,alex/cockroach,vaibhavarora/cockroach,cuongdo/cockroach,jess-edwards/cockroach,fengshao0907/cockroach,cuongdo/cockroach,XisiHuang/cockroach,yosiat/cockroach,jess-edwards/cockroach,paperstreet/cockroach,freakynit/cockroach,glycerine/cockroach,cockroachdb/cockroach,SustainFund/cockroach,c4pt0r/cockroach,vivekmenezes/cockroach,glycerine/cockroach,nkhuyu/cockroach,ajayaa/cockroach,nieyy/cockroach,alex/cockroach,jgautheron/cockroach,vaibhavarora/cockroach,jgautheron/cockroach,glycerine/cockroach,arjun4084346/cockroach,sunya123/cockroach,alex/cockroach,freakynit/cockroach,glycerine/cockroach,loucash/cockroach,mbonaci/cockroach,briceburg/cockroach,briceburg/cockroach,cockroachdb/cockroach,GokulSrinivas/cockroach,veteranlu/cockroach,yosiat/cockroach,petermattis/cockroach,vaibhavarora/cockroach,petermattis/cockroach,jess-edwards/cockroach,hassyma/cockroach,fengshao0907/cockroach,marcuswestin/cockroach,abhishekgahlot/cockroach,cuongdo/cockroach,arjun4084346/cockroach,chrisseto/cockroach,jess-edwards/cockroach,cockroachdb/cockroach,slavau/cockroach,jess-edwards/cockroach,paperstreet/cockroach,nkhuyu/cockroach,vaibhavarora/cockroach,alunarbeach/cockroach,jamesgraves/cockroach,SustainFund/cockroach,linearb/cockroach,marcuswestin/cockroach,alex/cockroach,maxlang/cockroach,alex/cockroach,bg451/cockroach,maxlang/cockroach,petermattis/cockroach,linearb/cockroach,arjun4084346/cockroach,abhishekgahlot/cockroach,Abioy/cockroach,nieyy/cockroach,nieyy/cockroach,jamesgraves/cockroach,nieyy/cockroach,veteranlu/cockroach,petermattis/cockroach,bg451/cockroach,bg451/cockroach,arypurnomoz/cockroach,Abioy/cockroach,hassyma/cockroach,chrisseto/cockroach,maxlang/cockroach,alunarbeach/cockroach,cockroachdb/cockroach,glycerine/cockroach,freakynit/cockroach,veteranlu/cockroach,veteranlu/cockroach,linearb/cockroach,yiixiansheng/cockroach,paperstreet/cockroach,glycerine/cockroach,veteranlu/cockroach,marcuswestin/cockroach,nieyy/cockroach,arypurnomoz/cockroach,paperstreet/cockroach,jmank88/cockroach,jmank88/cockroach,linearb/cockroach,paperstreet/cockroach,yiixiansheng/cockroach,freakynit/cockroach,bg451/cockroach,hassyma/cockroach,glycerine/cockroach,paperstreet/cockroach,briceburg/cockroach,marcuswestin/cockroach,mbertschler/cockroach,jgautheron/cockroach,briceburg/cockroach,il9ue/cockroach,arjun4084346/cockroach,c4pt0r/cockroach,loucash/cockroach,mbertschler/cockroach,loucash/cockroach,il9ue/cockroach,sunya123/cockroach,linearb/cockroach,glycerine/cockroach,cuongdo/cockroach,hassyma/cockroach,jess-edwards/cockroach,alunarbeach/cockroach,freakynit/cockroach,maxlang/cockroach,mbonaci/cockroach,loucash/cockroach,jgautheron/cockroach,marcuswestin/cockroach,vivekmenezes/cockroach,arjun4084346/cockroach,fengshao0907/cockroach,veteranlu/cockroach,linearb/cockroach,vivekmenezes/cockroach,bg451/cockroach,vaibhavarora/cockroach,cuongdo/cockroach,yiixiansheng/cockroach,jmank88/cockroach,Gokul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