I can't get it to reproduce right now. It may be a race condition, or maybe its on a timer before it reverts to the minibuffer? I'm not sure.

On Tue, May 12, 2015 at 11:09 AM, Eli Zaretskii <eliz@gnu.org> wrote:

> Date: Tue, 12 May 2015 10:40:34 -0700
> From: Michael Xavier <admin@michaelxavier.net>
>
> The example I encounter frequently is doing a TAGS file search and hitting TAB
> to complete. The tags system will fetch a completion and simultaneously log a
> message that its reading the TAGS file which will completely overwrite the
> completion.

But when it finishes reading the TAGS file, the completion is
re-displayed, right? At least that's what I see here (and expect).