Which line number owns connection boxes?

[ixchow]

Currently, the answer appears to be "none"

;!knitout-2
;;Carriers: 1 2

in 2
knit + f1 2
knit + f2 2

in 1
knit + f1 1
knit + f2 1
knit + f3 1
xfer f2 b1
xfer b1 fs1
xfer fs1 bs1
knit - f1 1

knit + f3 2

Suggested fix: yarn connections are owned by the box the yarn is going to. In-column connections that are not part of a yarn connection are owned by the box the yarn is coming from.