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

[Eli Zaretskii]

> From: Philip Kaludercic <philipk@posteo.net>
> Date: Sun, 13 Mar 2022 20:39:53 +0000
> Cc: 54374@debbugs.gnu.org
> 
> -      (while (< n 0)
> +      (while (and (< n 0) (< 1 (point)))

Please always use point-min, never a literal 1.

Thanks.