Reason for revert:
Didn't help.
Original issue's description:
> gclient: kill git fetch operation that hangs.
>
> This provides env variable GCLIENT_KILL_GIT_FETCH_AFTER
> that kills git fetch if it produces no output for that
> many seconds.
>
> Note that this is not final patch, but an experiment.
> See http://crbug.com/635641#c24 for the deployment plan.
>
> BUG=635641
> R=hinoka@chromium.org
>
> Committed: f8757b7e02
TBR=hinoka@chromium.org,hinoka@google.com
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=635641
Review-Url: https://codereview.chromium.org/2410853002
