Improved Mending broke future undo

[_Harwin_]

I know there are a lot of bugs with mending but I didn't see this one.

 

Seelah had a "Longsword +1" in her discard pile.

Then she cast Improved Mending to return it to her hand.

She recharged Improve Mending.

 

[Now I'm at what I'll call "Position A"]

I wanted to force the recharging of some of her armor so I hit the "discard" icon for ending the turn.  I discarded a card(forget which) then recharged armor. 

 

At that point I realized I didn't _want_ to discard the other card, so I hit cancel to put me back to "Position A".

 

I got the discarded card back, I got the armor back, I got put back in my main turn, and..... my Longsword +1 went back to my discard pile (but Improved Mending was still recharged).

 

Somehow the return of the Longsword +1 got stuck in the "cancel" stack for the end of turn?