+ # todo, this gives fake provided packages like mailx, and then
+ # fai ignores them.
+ # https://askubuntu.com/questions/21379/how-do-i-find-the-build-dependencies-of-a-package
+ apt-rdepends --build-depends --follow=DEPENDS $x|sed -rn 's/^\s*Build-Depends: (\S+).*/\1/p'