Ledger Lines misaligned when using arbitrary staff line distances

Ledger lines don't follow Staff Line Distance properly, either on Staff/part properties or after a Staff Type Change.
The code seems to cause a round up, and ledger lines only look aligned when Line Distance is set to multiples of 0.5 (i.e. 1.5 or 2.5).
When setting a staff line distance to 1.25, the ledger lines stay the same way as with line distance = 1. When going up to 1.5, ledger lines "snap" to their new position. In other words, the ledger lines distance stays the same when staff line distance is 1 or 1.49. Only when line distance reaches 1.5, ledger lines distance gets updated.

More easily observed with staff changes:

1) On a staff, input some notes that show ledger lines.
2) Apply a staff change before the notes
3) On the staff change inspector, hit the Line Distance arrow up
4) The staff line distance goes up to 1.25 but the ledger lines don't change
5) Hit Line Distance Up again
6) Staff line distance goes up to 1.5 and then the ledger lines are updated.