Make provision_devices failures abort the build

Make provision_devices failures abort the build

Otherwise if the devices are gone lots of tests will just fail.

Already fixed this for recipe based builders in crbug.com/393681

I don't know how to test this, but happy to write one if shown.

BUG=393681
NOTRY=True

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=283890

[luqui, 2014-07-14 23:11:23]

lgtm, +navabi for rubberstamp

[navabi1, 2014-07-15 00:16:57]

lgtm

[eseidel, 2014-07-15 00:29:37]

The CQ bit was checked by eseidel@chromium.org

[commit-bot: I haz the power, 2014-07-15 00:31:53]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/eseidel@chromium.org/390993003/1

[commit-bot: I haz the power, 2014-07-15 16:49:38]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_chromium_gn_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_gn_rel...)
  win8_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win8_chromium_rel/bui...)

[commit-bot: I haz the power, 2014-07-15 20:13:40]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-07-15 20:13:41]

Try jobs failed on following builders:
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)

[luqui, 2014-07-17 21:45:36]

The CQ bit was checked by luqui@chromium.org

[commit-bot: I haz the power, 2014-07-17 21:48:36]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/eseidel@chromium.org/390993003/1

[commit-bot: I haz the power, 2014-07-17 21:51:24]

Change committed as 283890