This shot from YVR Shoots just about confirms it.

But...what's wrong with this picture? As much as it brings back the shirt rip, it seems to be a mess with continuity as for Kara to change, she just removes her glasses. This could be some kind of dream sequence.
Now there are other pictures from another source. a Melissa Benoist fansite in Brazil showing more of the presser...


And meanwhile...there is a shot of Melissa, with a winter coat on doing the shirt rip...and with a cute smile. Maybe the cutest shirt rip ever.

UPDATE (12/3) Canadagraphs has put up more pictures and a summary of what is going on...POSSIBLE SPOILERS AS TO WHO WILL BE APPEARING AS GUESTS.
But it can be confirmed this is for the 100th episode which is titled "It's a Super Life," clearly a sort of Supergirl version of the classic film "It's a Wonderful Life."
Also, there's another pic of Melissa doing the rip in practice...again showing her cute smile.
