Again, this is an issue of permissions. The permissions of your ant process aren't the same as the permissions of the location where you are trying to execute the code to install the wiki. What I found was the best solution was to do
chown -R {username}:{username} /opt/zimbra
before running ant reset-the-world-stage2. This will also fix your problem with redo.log because it too wants to be a different permission level than the user running the ant process. | 
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