[hack] Make it a little more clear what's going on in workerController.ml.
[hack] Make it a little more clear what's going on in workerController.ml.

Summary: This syntax confused me and it was really hard to search for online, so I've changed it to be mildly easier.

Reviewed By: arxanas

Differential Revision: D16697974

fbshipit-source-id: 7437b55e8357cedc36afe02254bd9f545db02566

mroch/flow,mroch/flow,facebook/flow,mroch/flow,gabelevi/flow,gabelevi/flow,gabelevi/flow,facebook/flow,samwgoldman/flow,mroch/flow,facebook/flow,facebook/flow,samwgoldman/flow,facebook/flow,mroch/flow,mroch/flow,mroch/flow,facebook/flow,facebook/flow,gabelevi/flow,samwgoldman/flow,gabelevi/flow,samwgoldman/flow,gabelevi/flow,gabelevi/flow,samwgoldman/flow,samwgoldman/flow,samwgoldman/flow