setup-dchroot: Request unmerged /usr

Merged /usr is known to cause multiple packages to be misbuilt. As long
as we support unmerged /usr for user systems, we should mitigate
this class of bugs by using unmerged-/usr chroots on official buildds,
resulting in binary packages that work equally well on merged- or
unmerged-/usr user systems.

See:

https://bugs.debian.org/913229
https://udd.debian.org/cgi-bin/bts-usertags.cgi?user=md@linux.it&tag=usrmerge
thread at https://lists.debian.org/debian-devel/2018/11/msg00299.html

Signed-off-by: Simon McVittie <smcv@debian.org>
Signed-off-by: Julien Cristau <jcristau@debian.org>

diff --git a/modules/schroot/files/setup-dchroot b/modules/schroot/files/setup-dchroot
index c3cc504..8a6926b 100755 (executable)
--- a/modules/schroot/files/setup-dchroot
+++ b/modules/schroot/files/setup-dchroot
@@ -352,6 +352,7 @@ debootstrap \
     --include="$include" \
     --variant=buildd \
     --arch="$arch" \
+    --no-merged-usr \
     "$suite_alias" "$rootdir" "$mirror" "$script"
 echo "$tuple" > "$rootdir/etc/debian_chroot"
 echo "force-unsafe-io" > "$rootdir/etc/dpkg/dpkg.cfg.d/force-unsafe-io"