This is the highest priority of the escape actions because it's the thing you're
most likely to want to do upon hitting escape if you have a range selected.
Applying this to the staging/patch-building views is tricky: if we want this logic
for when a range of lines is selected, we'll also need to apply it when a hunk
is selected too. I still think it's worth it though: I've often accidentally
escaped from the staging view when trying to cancel a range selection.
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