Regenerate uploaded package at HackageDB

[Henning Thielemann]

I have uploaded
 http://hackage.haskell.org/cgi-bin/hackage-scripts/package/probability-0.2.1
  and then found that Haddock-2.0 emitted an error, that I did not
encounter since I have not upgraded to Haddock-2.0 so far. Now I have
uploaded the package again, which shall fix the Haddock problem. However
this seems not to trigger the build process again. How to do that?