As a follow-up, here's a much smaller version of the above patch. Thanks go to Petter for pointing me to the maintainer scripts documentation.
diff -r 9e5e6d9f91b1 debian/monkeysphere.postinst --- a/debian/monkeysphere.postinst Sat Jun 28 14:54:59 2014 -0500 +++ b/debian/monkeysphere.postinst Sat Jun 28 14:55:33 2014 -0500 @@ -21,12 +21,15 @@ monkeysphere fi - # try all available transitions: + # try all *necessary* transitions for trans in 0.23 0.28 ; do + if [[ "$2" == "" ]] || [[ "$trans" <= "$2" ]] + then /usr/share/monkeysphere/transitions/$trans || { \ RET=$? echo "Failed running transition script " \ "/usr/share/monkeysphere/transitions/$trans" >&2 exit $RET } + fi done