+# summary of how this script can be called:
+# * <new-preinst> `install'
+# * <new-preinst> `install' <old-version>
+# * <new-preinst> `upgrade' <old-version>
+# * <old-preinst> `abort-upgrade' <new-version>
+# for details, see http://www.debian.org/doc/debian-policy/ or
+# the debian-policy package
+