Upgrading from Solr 1.2 to 1.4.1

[johnmunir]

I'm using Solr 1.2.  If I upgrade to 1.4.1, must I re-index because of 
LUCENE-1142?  If so, how will this affect me if I don’t re-index (I'm using 
EnglishPorterFilterFactory)?  What about when I’m using non-English stammers 
from Snowball?
 
Beside the brief note "IMPORTANT UPGRADE NOTE" about this in CHANGES.txt, where 
can I read more about this?  I looked in JIRA, LUCENE-1142, there isn't much.
 
-M