connection pool: fixed a bug where deletion of nil entry was attempted if GOMAXPROCS>1.
connection pool: fixed a bug where deletion of nil entry was attempted if GOMAXPROCS>1.

ctrlaltdel121/radix,bpowers/radix,beni55/radix,mediocregopher/radix.v2,gabrielperezs/radix.improved,alphagov/radix,bpowers/radix,trigrass2/radix,mediocregopher/radix.v3,fzzy/radix,rightscale/radix