Avoid race comditions in background completer.
Avoid race comditions in background completer.

zhangmin510/vimium,Robinson10240/vimium,tuchangwei/vimium,Aleroniponi/vimium,borgified/vimium,borgified/vimium,VPashkov/vimium,PickRelated/vimium,mrmr1993/vimium,csmalin/vimium,PickRelated/vimium,decaffeinate-examples/vimium,hhsue/vimium,PrestanceDesign/vimium,decaffeinate-examples/vimium,Aleroniponi/vimium,smblott-github/vimium,smblott-github/vimium,Lw-Cui/vimium,philc/vimium,bkudria/vimium,PrestanceDesign/vimium,tuchangwei/vimium,poacher2k/vimium,mrmr1993/vimium,douglas-larocca/vimium,dimatter/vimium,willsALMANJ/vimium,decaffeinate-examples/vimium,borgified/vimium,willsALMANJ/vimium,gdh1995/vimium,PickRelated/vimium,elegantwww/vimium,wildeyes/vimium,gdh1995/vimium,justalittlenoob/vimium,hhsue/vimium,wildeyes/vimium,Aleroniponi/vimium,cyrixhero/vimium,Robinson10240/vimium,wildeyes/vimium,Lw-Cui/vimium,bkudria/vimium,elderbas/vimium,cyrixhero/vimium,dimatter/vimium,Lw-Cui/vimium,zhangmin510/vimium,cyrixhero/vimium,dimatter/vimium,poacher2k/vimium,philc/vimium,gdh1995/vimium,smblott-github/vimium,elegantwww/vimium,bkudria/vimium,justalittlenoob/vimium,VPashkov/vimium,douglas-larocca/vimium,douglas-larocca/vimium,VPashkov/vimium,justalittlenoob/vimium,tuchangwei/vimium,elegantwww/vimium,PrestanceDesign/vimium,zhangmin510/vimium,elderbas/vimium,csmalin/vimium,philc/vimium,hhsue/vimium,mrmr1993/vimium,willsALMANJ/vimium,csmalin/vimium,Robinson10240/vimium,elderbas/vimium,poacher2k/vimium