Upgraded RTokens might not pay DAO fees even if daoFeeRegistry has been set in Main. This is due to the change in the distribution total constraint in the _ensureSufficientTotal() function.
In previous versions, the check only required one of rTokenDist or rsrDist to be non-zero. The current implementation requires their sum to be greater than or equal to MAX_DISTRIBUTION. RTokens initialized with small distribution values in previous versions might not meet this new constraint after upgrading.
For small rTokenTotal and rsrTotal values, the DAO fee calculationin the distribute() function will round down to 0.
Consider implementing a post-upgrade call to _ensureSufficientTotal().
