ca-certificates 20161130+nmu1+deb9u1 removed the certificate we used
for testing.

Merge remote-tracking branch 'origin/bugfix/14404-remove-vagrant-disk-cache-setting' into stable (Fix-committed: #14404)

Thanks to Chris Lamb for the patch.

Since the cups 2.2.1-8+deb9u2 upload, the default profile confines
the mdns backend with the same rules (ix) as the cupsd binary,
so the rule for it we added manually will conflict. Let's drop it
and follow upstream's lead.

Merge branch 'bugfix/15590-14849-14720-14810-installer-fixes-for-3.9' into devel (Fix-committed: #15590, #14849, #14720, #14810)

That's the string sajolida and I came up with on XMPP today.

Interestingly, this command has been deprecated since December, but we forgot to update the doc. Doing that now.