bug#22324: 25.0.50; completion-category-defaults style doesn't override completion-styles (gets prepended instead)

[Stefan Monnier]

> Trying to honor the user's customization of 'completion-styles' makes
> a certain amount of sense. Though I don't know how much we honor it this
> way: if the user is relatively new, they might not even know to keep typing
> to see the fallback, after noting that their input does not give them the
> matches they expected.

Actually, I suspect it works better for new users than for old ones: new
users don't yet have a clear mental model of how Emacs's completion
works so they might expect something more like what you see with a web
browser search where adding more data can completely change the
proposed completions.

In contrast old-timers may indeed "know" that there won't be any
completions further down and will never reach the second style (to some
extent, that's how I got Richard to accept `partial-completion` in the
default).

> It's more of a critique of the whole "list of styles" design, admittedly.

I don't regret doing it because I don't think there was any other
way to activate `partial-completion` by default, but yes it has
its downsides.


        Stefan