Package: install-info Version: 6.7.0.dfsg.2-6 The post install is failing when dpkg is configured with a root and run as an unprivileged user. This is an issue partly with packaging and partly with the upstream package (I think). The upstream issue can be remedied with a patch in the packaging.
My suggestion for a fix is to modify update-info-dir such that it takes an argument (eg. --root <path>) prepend that argument to all file paths used. Then in the post install call update-info-dir with $PKG_ROOT as the argument, eg. update-info-dir --root $PKG_ROOT. Any fix will do though. Glenn