broken undo while manual routing

While routing manually, the undo action yields unexpected results under certain circumstances. To reproduce:

1) open PCB

2) choose a coarse net. E.g. 1mm

2) Add a footprint to the empty layout. E.g. 1W_Carbon_Resistor from the newlib library

3) make the rat_lines layer current

4) choose the line tool and connect the two pins of the resistor with a rat

5) make the top layer current

6) draw a track with two segments exactly aligned. PCB will merge aligned segments.

7) type [u] to engage the undo action.

Undo will fail to remove the merged segments correctly. The contour of the preview jumps to a node that is not the end of the track. Probably the merge of segments does not update the undo list properly. Curiously, undo of a completed tack is fine.

---<)kaimartin(>---