Undo stack fails to delete newly created 'way-segment'

[Edgemaster]

When using the Add node and Connect tool, running an undo after snapping to the centre of an existing way will cause the new node but not the new way-segment to be deleted.

Attempting to upload this will result in 412 precondition failed.

Steps to reproduce:
1) Create a node with the tool
2) Create a second, new node
3) Create a third new node on an already existing way. (Ctrl key modifier)
4) Undo this last action

[Gabriel Ebner <ge@…>]

Fixed in r353.