Bug#810715: pbuilder: pdebuild complains about DEBEMAIL

[Andreas Beckmann]

Followup-For: Bug #810715

DEBEMAIL is an environment variable used by devscripts, see
devscripts(1).

pbuilder also FTBFS with DEBEMAIL set while running the test suite
due to the deprecation warning messing up the expected output.
You could probably unset it while running the testsuite.

(Historically grown my sudoers config for pbuilder is
    Defaults!/usr/sbin/pbuilder env_keep += "HOME DEB_BUILD_OPTIONS"
    beckmann ALL = NOPASSWD: SETENV: /usr/sbin/pbuilder
I need $HOME for using ~/.pbuilderrc instead of /root/pbuilderrc and
DEB_BUILD_OPTIONS for obvious reasons, don't remember why I set SETENV,
probably because something was not working with testing reproducible
builds that need some environment changes)

Andreas