Mark thread for gc when associated value is nil
Mark thread for gc when associated value is nil

Not sure whether that can happen but seems more correct.

scalp42/byebug,k0kubun/byebug,miamiruby/byebug,guilherme/byebug,yui-knk/byebug,guilherme/byebug,guilherme/byebug,os97673/byebug,os97673/byebug,icebreaker/byebug,saisai/byebug,saisai/byebug,deivid-rodriguez/byebug,webdev1001/byebug,yui-knk/byebug,k0kubun/byebug,icebreaker/byebug,deivid-rodriguez/byebug,ozydingo/byebug,deivid-rodriguez/byebug,yui-knk/byebug,scalp42/byebug,ozydingo/byebug,miamiruby/byebug,k0kubun/byebug,webdev1001/byebug