Relanding changes to swarming isolate script and refactor of slave_utils

Relanding changes to swarming isolate script and refactor of slave_utils

Previous CL was missing return statements in GetMainRevision so
all waterfalls that utilized this script were not working.


BUG=chromium:633253
Committed: https://chromium.googlesource.com/chromium/tools/build/+/661c479e9dadfec6bf9c51a2b762eea23a5f5137

[eyaich1, 2016-10-05 23:42:55]

eyaich@chromium.org changed reviewers:
+ dpranke@chromium.org, kbr@chromium.org

[Ken Russell (switch to Gerrit), 2016-10-05 23:49:31]

Rubber stamp LGTM

In the future it would be better to upload the original CL verbatim, and then
apply the fixes in subsequent patch sets, so that reviewers can easily find the
fixes compared to the earlier version.

[eyaich1, 2016-10-06 16:16:55]

eyaich@chromium.org changed reviewers:
+ phajdan.jr@chromium.org

[eyaich1, 2016-10-06 16:16:56]

Adding Pawel for owners approval since I think Dirk is OOO.

[Dirk Pranke, 2016-10-06 16:22:13]

rs- lgtm.

[eyaich1, 2016-10-06 16:28:50]

The CQ bit was checked by eyaich@chromium.org

[commit-bot: I haz the power, 2016-10-06 16:28:54]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-06 16:36:18]

Description was changed from

==========
Relanding changes to swarming isolate script and refactor of slave_utils

Previous CL was missing return statements in GetMainRevision so
all waterfalls that utilized this script were not working.


BUG=chromium:633253
==========

to

==========
Relanding changes to swarming isolate script and refactor of slave_utils

Previous CL was missing return statements in GetMainRevision so
all waterfalls that utilized this script were not working.


BUG=chromium:633253

Committed:
https://chromium.googlesource.com/chromium/tools/build/+/661c479e9dadfec6bf9c...
==========

[commit-bot: I haz the power, 2016-10-06 16:36:21]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/chromium/tools/build/+/661c479e9dadfec6bf9c...

[tandrii(chromium), 2016-10-11 12:21:42]

tandrii@chromium.org changed reviewers:
+ tandrii@chromium.org

[tandrii(chromium), 2016-10-11 12:21:43]

https://codereview.chromium.org/2394093002/diff/40001/scripts/slave/recipe_mo...
File scripts/slave/recipe_modules/chromium_tests/steps.py (right):

https://codereview.chromium.org/2394093002/diff/40001/scripts/slave/recipe_mo...
scripts/slave/recipe_modules/chromium_tests/steps.py:1110: print 'Info: No chart
json present'
This is now printed while simulation_test is run, polluting output. If you
actually want these printed, these should be output using annotations such as:
  step_result.presentation.step_text += "whatever you want to print"