Bug#2532: Emacs fails to use `set -e' in postinst

[Ian Jackson <ian@chiark.chu.cam.ac.uk>]

Package: emacs
Version: ?

Thomas Krichel writes ("incomplete package installation"):
...
> bash# dpkg --install binary/emacs*
> (Reading database ... 17070 files and directories currently installed.)
> Preparing to replace emacs (using binary/emacs-19.29-4.deb) ...
> Unpacking replacement emacs ...
> install-info: failed to lock dir for editing! File exists
> install-info: failed to lock dir for editing! File exists
>
>   this repeats 10 times, then appears:

This shows that emacs is failing to spot the failure of the first call
to install-info and is going on to try the others.  It should stop
after the first one.

Ian.