dh_prep - perform cleanups in preparation for building a binary package
dh_prep [debhelper options] [-Xitem]
dh_prep is a debhelper program that performs some file cleanups in
preparation for building a binary package. (This is what dh_clean -k
used to do.) It removes the package build directories, debian/tmp,
and some temp files that are generated when building a binary package.
It is typically run at the top of the binary-arch and binary-indep targets,
or at the top of a target such as install that they depend on.
Exclude files that contain item anywhere in their filename from being
deleted, even if they would normally be deleted. You may use this option
multiple times to build up a list of things to exclude.