cb5aac620c
- PresentsInvoker decides it's empty - It waits on other dependencies - During the wait, something (probably from one of the other dependencies) posts to the PresentsInvoker - We loop back around, the dependencies are empty - We end early, with the posted bit still to be done... So... after waiting, do a quick check for emptyness and if not satisfied, start the whole dern cycle over. git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@6005 542714f4-19e9-0310-aa3c-eee0fc999fb1