make Watchman.re_init return a result
make Watchman.re_init return a result

Summary: continuing to push `result` through the call stack

Reviewed By: samwgoldman

Differential Revision: D28259332

fbshipit-source-id: 8217dc139af876b78b3360b47c8c14dcc0e6a68f

mroch/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,facebook/flow