Comment 4 for bug 643303

I tried to fix the bug by simple detecting the current core schema and "i" and the iterating through all update scripts in form of 'core_"i"_"i+1"' its simple and straight forward. No looking for paths and leaving us to actually only worry about upgrade +1 increasing upgrade scripts. If the basic idea is OK I can propose for merging.
https://code.edge.launchpad.net/~seif/zeitgeist/fix-643303