hooks: purge packages before creating list of included packages

Author: alfonsosanchezbeato

hooks/600-no-debian.chroot

@@ -6,6 +6,11 @@ set -ex
 
 echo "I: Removing the debian legacy"
 
+# dpkg-deb and dpkg purposefully left behind. Ideally we would also remove
+# libapt-pkg6.0, but that would break our ABI as unfortunately we shipped it in
+# previous revisions of core20.
+dpkg --purge --force-depends apt debconf
+
 # store manifest of all installed packages
 install -m755 -d usr/share/snappy
 dpkg -l > usr/share/snappy/dpkg.list
@@ -29,9 +34,6 @@ dpkg -l > usr/share/snappy/dpkg.list
   dpkg-query -W --showformat='- ${binary:Package}=${Version}\n'
 } > /usr/share/snappy/dpkg.yaml
 
-# dpkg-deb and dpkg purposefully left behind
-dpkg --purge --force-depends apt libapt-pkg5.0 debconf
-
 rm -r \
         var/lib/dpkg \
         var/log/apt