The rules run as the unprivileged build user, so an ownership change
they make during the build (a sysroot chown) failed per file with
EPERM, spamming the build view and log and silently not happening.
Wrap the build step in fakeroot like the binary step already is, and
share one session state between the two — the way dpkg-buildpackage
-rfakeroot wraps every rules target: the chown succeeds faked and
carries into the .deb assembly. With the context's own user the
build step stays bare. The state file lives in the staged build
root, outside the package tree, and is removed before each build so
an interrupted previous attempt cannot seed the session.
vhaudiquet
5f36a54e7c