Deleting files from .orig on unpack?

[Jonathan Niehof <jtniehof@gmail.com>]

I'm working with a package where upstream uses a flat Makefile and the
Debian package has been converted to automake. This means the Makefile
from the .orig.tar.gz gets clobbered in the build process, and then
removed entirely on clean. So build; clean isn't a no-op. I see
several ways to deal with this:
1) Ignore it and be happy, but since clean doesn't actually restore
the tree isn't this a policy violation?
2) Add a patch that does nothing but axe the Makefile (already
converted to 3.0 quilt, so this would be done on unpack). Seems ugly.
3) Add a bunch of rules logic to back up the shipped makefile on bulid
and restore it on clean
4) Maybe there's some magical invocation to get dpkg to delete it at
source unpack time? I can't find anything relevant though.

Suggestions on the best approach (or a 5?) Upstream seems dormant, so
convincing them to switch to automake is probably not on the agenda.