bug#60359: 29.0.60; completion-auto-select set to t skips first argument when completing files

[Juri Linkov]

> Thanks for your bug report.  If I set completion-auto-select in emacs -Q,
> C-x C-f C TAB (or TAB TAB, depending on the value of
> completion-auto-select) in the Emacs repository behaves as
> expected. However, C-x C-f src/ TAB does not.  Is the latter case what you
> have in mind, or do I misunderstand what you mean?  If not, the attached
> patch should fix that bug.

Please omit the message only in case when the completions buffer is shown,
then the user will see there are more completions.  But after typing e.g.
`M-x man TAB` that otherwise does nothing the user should see the message.
IOW, in case of `completion-auto-help` please use the same condition
`(and (eq this-command last-command) completion-auto-help)` as used
to pop up the completions.