bug#38457: 27.0.50; dabbrev-expand regression due to message change

[Eli Zaretskii]

> Date: Tue, 17 Dec 2019 14:27:38 +0800
> From: HaiJun Zhang <netjune@outlook.com>
> Cc: 38457@debbugs.gnu.org
> 
> For the original bug of this thread, I have a feature request: 
> I would like dabbrev-expand to don’t display the messages when minibuffer is 
> active. It is annoying in everyday
> use. It cause flickers. I suffer from it too long.

Is that wise?  dabbrev-expand could take quite some time, if it
starts looking in other buffers and there are a lot of them.  If it
keeps silence, you will see Emacs frozen without any indication of
what's going on.  People will consider this a bug and complain.