deb: build the rules as an unprivileged user in pkh chroots, the
same way Launchpad's buildds and sbuild do - setpriv drops to an
on-demand pkh-build user owning the staged tree, the scratch HOME
and the ccache; dependency installation and quilt stay root.
Validated by the e2e canary: coreutils (which refuses a root
configure) now passes.
* rootless-builds:
test: drop the coreutils xfail, rootless builds clear it
deb: run the user probes through sh with stderr dropped
deb: build the rules as an unprivileged user in pkh chroots
vhaudiquet
7055d69152