fix #26516: crash on repitch

Good catch!  I think the best thing is to do what is done for up/down - automatically "rewinding" to the start of the tie at the beginning of the whole operation (and I can fix it in both places to not go into an infinite loop if a note is tied to itself).

Another possibility is to assume the user is doing this on purpose, and break the tie back from the initially selected note.  But I think I'll try the first solution.