Sometimes, I'm debugging an intermittent test failure on Try, and so I do Try pushes with added logging to try and diagnose the problem. Since the failure is intermittent, I need to retrigger the job many times to trigger to failing scenario. Right now, I have to wait for the build and the initial run of the job before I can retrigger it. Since I already know I will want to retrigger it when I push, it would be nice if I had a way to specify the retriggers as soon as I push (either through the try syntax, or in the Treeherder UI but available as soon as I pushed).
How about "try: yadda yadda -u mochitest-5 --rebuild 20"? If bug 1177653 had been deployed, you could even have found out about it on the trychooser page :)