create-review: prompt to update an existing review instead

[QuLogic]

I ran fbrnch create-review for a review I'd already opened (having forgotten about the update-review command); it then printed out:

$ fbrnch create-review -S python-pyogrio.spec 
checking for existing reviews...
Existing review(s):
Review Request: python-pyogrio - Vectorized spatial vector file format I/O using GDAL/OGR (ASSIGNED)
https://bugzilla.redhat.com/show_bug.cgi?id=2294379

Press Enter to continue: 

I didn't realize Enter to continue meant to continue creating a new review and ended up filing a duplicate review.

If the review (as in this case) was opened by me, it would be more convenient if fbrnch switched (automatically or by prompt) to update-review mode instead of creating the duplicate.

[juhp]

Makes sense, let me see what I can do

[juhp]

Okay, I am making create-review safer in 1.5.1: it will now error unless you pass --force
when existing reviews exist. I started doing the auto-switch to update-review, but I feel
it is a bit complicated and possibly surprising behavior. Though admittedly I don't currently
check who does update-review either hm

Anyway I think this should address your main concern of making it harder to create a duplicate review by mistake.