how to rerun buildbot

edit

I was trying to contribute a module to opencv_extra(see https://github.com/opencv/opencv_cont...). At first, it failed because of a bug. Then I modified my local repo and "git push -f origin master" as people suggested. After that, the failed build history disappear, but the buildbot didn't rerun to build for a long time. Could anyone pls tell me how to force it to rerun? many thx!!!!