don't set DEBEMAIL in /etc/pbuilderrc

That's pretty much it.

The reason is that, if you do set DEBEMAIL pbuilder/cowbuilder configuration option (most likely, to the same value of your $DEBEMAIL envvar) you will end up generating .changes file containing fields like:

    Maintainer: Stefano Zacchiroli <zack@debian.org>
    Changed-By: Stefano Zacchiroli <zack@debian.org>

even when you're not the maintainer, e.g. when the maintainer is a team address or when you are doing an NMU (which I've been doing quite a lot recently).

I discovered this thanks to Ana about a month ago and it quite shocked me, since I've been using the same pbuilder (and then cowbuilder) configuration for quite a while (years ...) without realizing that.

The complicity of a missing lintian check has surely helped (wishlist bug filed) as well as a weird/buggy behavior on the *builder side (there are some bugs on that line, I just haven't taken the time yet to understand what should be the correct behavior).

Bottom line: just check whether you are screwing up .changes file due to overzealous attitude in builder configuration