System brackets and connected barlines made a mess of when new instrument added in the middle

1. Create new score from sting orchestra template (see bracket1.png).
2. Press [i], add second viola beside first.

Expected result: bracket and connected barlines will continue to include Contrabass (see bracket2.png). Current result: bracket and barlines are positioned based on number of staves, not which staves they are connected to, so bracket only covers down to Violoncello, and Contrabass staff is disconnected in terms of barlines (see bracket3.png).