"Zakariyah Ali via GitGitGadget" [off-list ref] writes:

This matches standard shell filename completion behavior, where dotfiles
are hidden by default unless the user starts their input with a dot.

OK, with this rationale added, I no longer have problem with the
proposed new behaviour.

As I'm not going to give a serious review  on the patch body itself,
I would really appreciate somebody more knowledgeable on the
existing bach completion code than I am to take a look.

Thanks.