Hello.
I've got a problem with computing new warnings functional.
When I add a new PMD rule to my ruleset, I get odd results.
Test case:

1. Start the first build.
   See summary and full results.
2. Add a new PMD rule to rule set and start the second build.
   Rule 'LongVariable' was added. The summary contains only 192 new warnings instead of 267 (==3126-2859).
   Moreover, full result contains 267 warning for new 'LongVariable' rule (match against first result).
3. Go to job configuration, check 'Use delta for new warnings' check box and start the third build.
   The result changed.
   The summary contains both 192 and 267 new warnings on the same page.
   Besides, link '267 new warnings' opens a page with 192 new warnings.
   I suppose that the number of new warning should always be 267 in the example.