Debnest provides a build system to create debian binary packages such that original upstream sources include debian source packages, i.e. .dsc and other files such as .orig.tar.gz and diff.gz, or .tar.gz. in build-time, this system unpacks debian source packages by 'dpkg-source -x' and propagates policy-defined targets of debian/rules into the unpacked sources.

this allows you to:
* manage your own files under debian/ such as debian/rules
debian/control, debian/changelog and so on separately away from
their original packages.
* create your own tuned packages with your own pre-defined
deb_build_options, cc in your debian/rules from their
original packages without specifying any environment
variables in each build-time.
* create your own tuned packages with patches to their
original sources as well as to debian/* files, separating
them completely away from their original source packages.
* make it possible to redistribute your modified debian package
based on another debian source package which restricts
source-code from being distributed in modified form _only_ by
the distribution of "patch files" with the source code for the
purpose of modifying the program at build time.