bug#30186: 27.0.50; Password is not hidden in read-passwd

[Eli Zaretskii]

> Date: Fri, 26 Jan 2018 18:37:02 +0000
> From: Alan Mackenzie <acm@muc.de>
> Cc: 30186@debbugs.gnu.org
> 
> The problem here appears to be a fundamental design bug in Emacs: that
> text properties are regarded as part of the buffer rather than something
> accompanying the buffer, as overlays are.

It's not a bug, it's a feature (and a very important one).