Verify if our dpkg patch is still needed with today's overlayfs
A few years have passed since we patched dpkg to work around this bug: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=836211
It would be nice to verify if the issue is still present in today's overlayfs. If not, then we drop the patch and close the Debian bug. If yes, then we update the Debian bug with current findings.
To verify you need two versions of a package with a specific path that is a directory in the first version and a file in the second version. You install the first version in a schroot, then you open that same schroot with overlayfs enabled and you try to install the second version. (And you need dpkg withtout the patch obviously!)