bug#30190: 27.0.50; term run in line mode shows user passwords

[Eli Zaretskii]

> From: Tino Calancha <tino.calancha@gmail.com>
> Cc: 30190@debbugs.gnu.org,  rms@gnu.org,  npostavs@users.sourceforge.net
> Date: Sat, 10 Mar 2018 22:17:13 +0900
> 
> Bad behaviour:
> [sudo] password for foo:
> # This throws 'command not found' BUT _sometimes_ you are prompted for
> # your password in the minibuffer.
> # Note: This happens in a dumb shell buffer as well.

What happens if you have a command (say, a shell script) that prompts
for something that is not a password with a prompt that starts with
text that matches the regexp -- what is the behavior then, after your
changes?  What I see here is that the filter redirects that to the
minibuffer, and doesn't show the text I type, unlike what happened
before your changes.  Wouldn't that look like a bug and cause bug
reports?

I'm also worried by the "_sometimes_" part: does it mean the behavior
is not deterministic?  Why?

> Whatever misfunction of my patch should happen in a dumb shell buffer
> started with:
> M-x shell

Yes, but two wrongs don't make a right...