Disable <Tab> if Fuzz

[orbisvicis]

There tends to be no common prefix with fuzzy mapping, but I have a reflex of tab-completing. Perhaps tab-complete should do nothing if it shortens the current match?

[paradigm]

Not sure what order you'll view these in, so I'm going to prefix all of the
recent issues you've made with:

I've got a skybison 2.0 ~90% done with many improvements. There's some
(external) blockers keeping me from finishing and publishing it (and a bunch of
other vim projects of mine...) immediately, but I fully plan to do so as soon
as is reasonably possible.

---

I agree, the way it acts now is silly. I'll attempt to remedy this for 2.0.
The length check you proposed seems like a very clean solution.