[qa] Handle disconnect_node race
[qa] Handle disconnect_node race

Several tests call disconnect_nodes() on each node-pair in rapid
succession, resulting in a race condition if a node disconnects a peer
in-between the calculation of the nodeid's to disconnect and the
invocation of the disconnectnode rpc call.  Handle this.

sstone/bitcoin,midnightmagic/bitcoin,RHavar/bitcoin,DigitalPandacoin/pandacoin,kazcw/bitcoin,EthanHeilman/bitcoin,n1bor/bitcoin,vertcoin/vertcoin,thrasher-/litecoin,fujicoin/fujicoin,myriadcoin/myriadcoin,untrustbank/litecoin,lateminer/bitcoin,anditto/bitcoin,bitcoinsSG/bitcoin,domob1812/bitcoin,jonasschnelli/bitcoin,sipsorcery/bitcoin,nikkitan/bitcoin,alecalve/bitcoin,Flowdalic/bitcoin,kallewoof/bitcoin,ElementsProject/elements,OmniLayer/omnicore,mruddy/bitcoin,practicalswift/bitcoin,jmcorgan/bitcoin,vmp32k/litecoin,sipsorcery/bitcoin,untrustbank/litecoin,n1bor/bitcoin,bitcoinsSG/bitcoin,jnewbery/bitcoin,vertcoin/vertcoin,lateminer/bitcoin,domob1812/bitcoin,jnewbery/bitcoin,nikkitan/bitcoin,jlopp/statoshi,instagibbs/bitcoin,pataquets/namecoin-core,RHavar/bitcoin,BTCGPU/BTCGPU,untrustbank/litecoin,afk11/bitcoin,prusnak/bitcoin,tjps/bitcoin,OmniLayer/omnicore,jamesob/bitcoin,randy-waterhouse/bitcoin,afk11/bitcoin,jtimon/bitcoin,Kogser/bitcoin,peercoin/peercoin,namecoin/namecore,fujicoin/fujicoin,vertcoin/vertcoin,myriadteam/myriadcoin,ajtowns/bitcoin,jonasschnelli/bitcoin,untrustbank/litecoin,anditto/bitcoin,GroestlCoin/GroestlCoin,mm-s/bitcoin,qtumproject/qtum,sipsorcery/bitcoin,bitcoin/bitcoin,alecalve/bitcoin,particl/particl-core,FeatherCoin/Feathercoin,prusnak/bitcoin,mm-s/bitcoin,andreaskern/bitcoin,pstratem/bitcoin,Flowdalic/bitcoin,practicalswift/bitcoin,GroestlCoin/GroestlCoin,MeshCollider/bitcoin,kallewoof/bitcoin,pataquets/namecoin-core,domob1812/bitcoin,domob1812/namecore,cdecker/bitcoin,sstone/bitcoin,digibyte/digibyte,jambolo/bitcoin,MarcoFalke/bitcoin,droark/bitcoin,rnicoll/dogecoin,sstone/bitcoin,tjps/bitcoin,rnicoll/bitcoin,namecoin/namecore,MeshCollider/bitcoin,pstratem/bitcoin,fanquake/bitcoin,jambolo/bitcoin,fanquake/bitcoin,prusnak/bitcoin,kallewoof/bitcoin,jambolo/bitcoin,Xekyo/bitcoin,myriadcoin/myriadcoin,jonasschnelli/bitcoin,ahmedbodi/vertcoin,mm-s/bitcoin,yenliangl/bitcoin,rnicoll/bitcoin,qtumproject/qtum,mruddy/bitcoin,gjhiggins/vcoincore,bespike/litecoin,GlobalBoost/GlobalBoost,ElementsProject/elements,r8921039/bitcoin,DigitalPandacoin/pandacoin,monacoinproject/monacoin,gjhiggins/vcoincore,JeremyRubin/bitcoin,ahmedbodi/vertcoin,namecoin/namecoin-core,EthanHeilman/bitcoin,midnightmagic/bitcoin,practicalswift/bitcoin,litecoin-project/litecoin,fanquake/bitcoin,fanquake/bitcoin,ajtowns/bitcoin,jnewbery/bitcoin,peercoin/peercoin,particl/particl-core,domob1812/huntercore,GroestlCoin/GroestlCoin,GlobalBoost/GlobalBoost,andreaskern/bitcoin,andreaskern/bitcoin,dscotese/bitcoin,myriadteam/myriadcoin,myriadteam/myriadcoin,wellenreiter01/Feathercoin,randy-waterhouse/bitcoin,domob1812/namecore,vmp32k/litecoin,alecalve/bitcoin,instagibbs/bitcoin,namecoin/namecore,ajtowns/bitcoin,ahmedbodi/vertcoin,myriadteam/myriadcoin,rnicoll/bitcoin,qtumproject/qtum,Xekyo/bitcoin,bitcoinsSG/bitcoin,domob1812/huntercore,OmniLayer/omnicore,MarcoFalke/bitcoin,pataquets/namecoin-core,CryptArc/bitcoin,jnewbery/bitcoin,litecoin-project/litecoin,jambolo/bitcoin,jlopp/statoshi,domob1812/bitcoin,MarcoFalke/bitcoin,kazcw/bitcoin,guncoin/guncoin,ericshawlinux/bitcoin,cdecker/bitcoin,cdecker/bitcoin,fujicoin/fujicoin,droark/bitcoin,joshrabinowitz/bitcoin,Xekyo/bitcoin,vertcoin/vertcoin,jtimon/bitcoin,monacoinproject/monacoin,myriadteam/myriadcoin,CryptArc/bitcoin,CryptArc/bitcoin,dscotese/bitcoin,GroestlCoin/bitcoin,r8921039/bitcoin,Sjors/bitcoin,n1bor/bitcoin,h4x3rotab/BTCGPU,namecoin/namecoin-core,EthanHeilman/bitcoin,GroestlCoin/bitcoin,thrasher-/litecoin,RHavar/bitcoin,namecoin/namecoin-core,droark/bitcoin,sebrandon1/bitcoin,CryptArc/bitcoin,jamesob/bitcoin,cdecker/bitcoin,wellenreiter01/Feathercoin,OmniLayer/omnicore,Bushstar/UFO-Project,h4x3rotab/BTCGPU,mitchellcash/bitcoin,vmp32k/litecoin,Bushstar/UFO-Project,achow101/bitcoin,pstratem/bitcoin,MeshCollider/bitcoin,qtumproject/qtum,vmp32k/litecoin,tjps/bitcoin,guncoin/guncoin,jamesob/bitcoin,lateminer/bitcoin,MeshCollider/bitcoin,lbryio/lbrycrd,mruddy/bitcoin,sstone/bitcoin,monacoinproject/monacoin,guncoin/guncoin,anditto/bitcoin,afk11/bitcoin,gjhiggins/vcoincore,rnicoll/dogecoin,myriadcoin/myriadcoin,thrasher-/litecoin,ajtowns/bitcoin,tecnovert/particl-core,lateminer/bitcoin,mitchellcash/bitcoin,lbryio/lbrycrd,jlopp/statoshi,particl/particl-core,anditto/bitcoin,domob1812/huntercore,bitcoinknots/bitcoin,untrustbank/litecoin,mitchellcash/bitcoin,untrustbank/litecoin,apoelstra/bitcoin,apoelstra/bitcoin,n1bor/bitcoin,jmcorgan/bitcoin,tjps/bitcoin,Kogser/bitcoin,bitcoin/bitcoin,ericshawlinux/bitcoin,practicalswift/bitcoin,jtimon/bitcoin,nikkitan/bitcoin,jamesob/bitcoin,namecoin/namecore,jambolo/bitcoin,prusnak/bitcoin,jtimon/bitcoin,Kogser/bitcoin,h4x3rotab/BTCGPU,prusnak/bitcoin,yenliangl/bitcoin,afk11/bitcoin,jlopp/statoshi,gjhiggins/vcoincore,Christewart/bitcoin,RHavar/bitcoin,BTCGPU/BTCGPU,ElementsProject/elements,fujicoin/fujicoin,GlobalBoost/GlobalBoost,peercoin/peercoin,bitcoin/bitcoin,jlopp/statoshi,dscotese/bitcoin,Flowdalic/bitcoin,jtimon/bitcoin,droark/bitcoin,midnightmagic/bitcoin,GlobalBoost/GlobalBoost,sebrandon1/bitcoin,jmcorgan/bitcoin,tecnovert/particl-core,achow101/bitcoin,rawodb/bitcoin,cdecker/bitcoin,Sjors/bitcoin,GroestlCoin/GroestlCoin,namecoin/namecoin-core,bitcoinknots/bitcoin,rawodb/bitcoin,jmcorgan/bitcoin,EthanHeilman/bitcoin,AkioNak/bitcoin,apoelstra/bitcoin,Bushstar/UFO-Project,h4x3rotab/BTCGPU,achow101/bitcoin,vertcoin/vertcoin,qtumproject/qtum,rnicoll/dogecoin,DigitalPandacoin/pandacoin,lbryio/lbrycrd,alecalve/bitcoin,BTCGPU/BTCGPU,domob1812/bitcoin,jmcorgan/bitcoin,FeatherCoin/Feathercoin,dscotese/bitcoin,cdecker/bitcoin,DigitalPandacoin/pandacoin,alecalve/bitcoin,AkioNak/bitcoin,andreaskern/bitcoin,RHavar/bitcoin,Sjors/bitcoin,FeatherCoin/Feathercoin,mruddy/bitcoin,AkioNak/bitcoin,domob1812/namecore,jnewbery/bitcoin,digibyte/digibyte,ericshawlinux/bitcoin,yenliangl/bitcoin,lbryio/lbrycrd,sstone/bitcoin,mm-s/bitcoin,MarcoFalke/bitcoin,pataquets/namecoin-core,apoelstra/bitcoin,namecoin/namecore,kallewoof/bitcoin,joshrabinowitz/bitcoin,thrasher-/litecoin,Christewart/bitcoin,BTCGPU/BTCGPU,kallewoof/bitcoin,h4x3rotab/BTCGPU,AkioNak/bitcoin,peercoin/peercoin,guncoin/guncoin,Xekyo/bitcoin,AkioNak/bitcoin,domob1812/huntercore,domob1812/namecore,rawodb/bitcoin,MarcoFalke/bitcoin,fujicoin/fujicoin,mitchellcash/bitcoin,FeatherCoin/Feathercoin,Kogser/bitcoin,droark/bitcoin,rawodb/bitcoin,Xekyo/bitcoin,MeshCollider/bitcoin,joshrabinowitz/bitcoin,afk11/bitcoin,jonasschnelli/bitcoin,ahmedbodi/vertcoin,bespike/litecoin,thrasher-/litecoin,qtumproject/qtum,litecoin-project/litecoin,JeremyRubin/bitcoin,Kogser/bitcoin,fanquake/bitcoin,jtimon/bitcoin,kallewoof/bitcoin,dscotese/bitcoin,instagibbs/bitcoin,r8921039/bitcoin,joshrabinowitz/bitcoin,lateminer/bitcoin,ElementsProject/elements,ajtowns/bitcoin,litecoin-project/litecoin,GroestlCoin/bitcoin,EthanHeilman/bitcoin,nikkitan/bitcoin,digibyte/digibyte,rnicoll/bitcoin,Bushstar/UFO-Project,namecoin/namecore,prusnak/bitcoin,domob1812/huntercore,digibyte/digibyte,mitchellcash/bitcoin,Christewart/bitcoin,Flowdalic/bitcoin,FeatherCoin/Feathercoin,CryptArc/bitcoin,yenliangl/bitcoin,jlopp/statoshi,EthanHeilman/bitcoin,n1bor/bitcoin,fanquake/bitcoin,myriadcoin/myriadcoin,peercoin/peercoin,vmp32k/litecoin,practicalswift/bitcoin,monacoinproject/monacoin,thrasher-/litecoin,ElementsProject/elements,MeshCollider/bitcoin,namecoin/namecoin-core,ericshawlinux/bitcoin,randy-waterhouse/bitcoin,RHavar/bitcoin,h4x3rotab/BTCGPU,Bushstar/UFO-Project,midnightmagic/bitcoin,yenliangl/bitcoin,particl/particl-core,kazcw/bitcoin,Christewart/bitcoin,Kogser/bitcoin,mruddy/bitcoin,tecnovert/particl-core,jmcorgan/bitcoin,DigitalPandacoin/pandacoin,peercoin/peercoin,kazcw/bitcoin,ericshawlinux/bitcoin,monacoinproject/monacoin,anditto/bitcoin,domob1812/bitcoin,n1bor/bitcoin,sstone/bitcoin,nikkitan/bitcoin,randy-waterhouse/bitcoin,GroestlCoin/bitcoin,bitcoin/bitcoin,Sjors/bitcoin,digibyte/digibyte,BTCGPU/BTCGPU,jambolo/bitcoin,Kogser/bitcoin,pstratem/bitcoin,GlobalBoost/GlobalBoost,tjps/bitcoin,lateminer/bitcoin,bitcoin/bitcoin,vertcoin/vertcoin,wellenreiter01/Feathercoin,instagibbs/bitcoin,bitcoinknots/bitcoin,Flowdalic/bitcoin,instagibbs/bitcoin,tjps/bitcoin,bespike/litecoin,apoelstra/bitcoin,gjhiggins/vcoincore,pataquets/namecoin-core,pstratem/bitcoin,achow101/bitcoin,achow101/bitcoin,jamesob/bitcoin,myriadcoin/myriadcoin,andreaskern/bitcoin,achow101/bitcoin,JeremyRubin/bitcoin,rnicoll/bitcoin,monacoinproject/monacoin,vmp32k/litecoin,randy-waterhouse/bitcoin,sebrandon1/bitcoin,bitcoinknots/bitcoin,domob1812/huntercore,wellenreiter01/Feathercoin,joshrabinowitz/bitcoin,anditto/bitcoin,gjhiggins/vcoincore,namecoin/namecoin-core,rawodb/bitcoin,andreaskern/bitcoin,kazcw/bitcoin,lbryio/lbrycrd,rawodb/bitcoin,GroestlCoin/bitcoin,litecoin-project/litecoin,digibyte/digibyte,practicalswift/bitcoin,ahmedbodi/vertcoin,sipsorcery/bitcoin,lbryio/lbrycrd,GroestlCoin/GroestlCoin,bespike/litecoin,bitcoinknots/bitcoin,domob1812/namecore,midnightmagic/bitcoin,AkioNak/bitcoin,tecnovert/particl-core,qtumproject/qtum,jamesob/bitcoin,DigitalPandacoin/pandacoin,myriadcoin/myriadcoin,Christewart/bitcoin,bitcoinsSG/bitcoin,ElementsProject/elements,alecalve/bitcoin,randy-waterhouse/bitcoin,Kogser/bitcoin,kazcw/bitcoin,particl/particl-core,bespike/litecoin,ajtowns/bitcoin,JeremyRubin/bitcoin,bitcoin/bitcoin,sipsorcery/bitcoin,rnicoll/dogecoin,nikkitan/bitcoin,bitcoinsSG/bitcoin,r8921039/bitcoin,fujicoin/fujicoin,Kogser/bitcoin,jonasschnelli/bitcoin,Kogser/bitcoin,Kogser/bitcoin,Flowdalic/bitcoin,myriadteam/myriadcoin,MarcoFalke/bitcoin,Christewart/bitcoin,GroestlCoin/GroestlCoin,sipsorcery/bitcoin,CryptArc/bitcoin,GlobalBoost/GlobalBoost,JeremyRubin/bitcoin,sebrandon1/bitcoin,joshrabinowitz/bitcoin,tecnovert/particl-core,wellenreiter01/Feathercoin,apoelstra/bitcoin,Xekyo/bitcoin,yenliangl/bitcoin,guncoin/guncoin,tecnovert/particl-core,domob1812/namecore,ericshawlinux/bitcoin,afk11/bitcoin,bitcoinsSG/bitcoin,rnicoll/bitcoin,mruddy/bitcoin,sebrandon1/bitcoin,lbryio/lbrycrd,BTCGPU/BTCGPU,wellenreiter01/Feathercoin,JeremyRubin/bitcoin,GlobalBoost/GlobalBoost,Sjors/bitcoin,droark/bitcoin,OmniLayer/omnicore,bespike/litecoin,midnightmagic/bitcoin,OmniLayer/omnicore,FeatherCoin/Feathercoin,Bushstar/UFO-Project,rnicoll/dogecoin,mm-s/bitcoin,ahmedbodi/vertcoin,pataquets/namecoin-core,r8921039/bitcoin,mitchellcash/bitcoin,litecoin-project/litecoin,dscotese/bitcoin,Kogser/bitcoin,r8921039/bitcoin,pstratem/bitcoin,guncoin/guncoin,sebrandon1/bitcoin,particl/particl-core,instagibbs/bitcoin,mm-s/bitcoin,GroestlCoin/bitcoin