bug#54374: [External] : bug#54374: 29.0.50; previous-completion fails at beginning of completions buffer

[Drew Adams]

> when point is at the beginning of the completion buffer,
> then previous-completion switches to the minibuffer.

Not good.  Keys that cycle among completions should
do exactly that.  And they should wrap around, at
least by default (with a user option to not do that).

If point is at bob then backward cycling should move
to the last completion.

> But if point is at the first completion, then previous-completion wraps
> to the last completion.  Shouldn't point at the beginning of the buffer
> wrap to the last completion as well?

Of course it should.  If point is there or at any
place before the first completion then backward
cycling should wrap around to the last completion.