Last modified: 2013-12-04 01:19:14 UTC
Give potential extension tags (non-html tags) a very high syntactic precedence. See http://www.mediawiki.org/wiki/Parsoid/Todo:Extension_tag_precedence for the details.
Lowering the priority, as the syntactic precedence does not matter very often in practice. See http://en.wikipedia.org/wiki/User:GWicke/Martian_endtags for stats on an English Wikipedia dump.
Some of these cases should have been handled with all the recent extension parsing fixes starting with https://gerrit.wikimedia.org/r/#/c/52274/ To be verified more thoroughly.
There have not been any issues in this area in the last months. Closing as fixed.