Revert 236860 "Roll swarming_client @ 4727bd5a1a67726d5c64d292f9..."

Revert 236860 "Roll swarming_client @ 4727bd5a1a67726d5c64d292f9..."

> Roll swarming_client @ 4727bd5a1a67726d5c64d292f970590ddb1b6a98.
> 
> $ git log e98b112..4727bd5a1a --date=short --format="%ad %ae %s" | sed 's/@chromium\.org//'
> 2013-11-22 maruel Stop making the tree read-only when 'read_only': True is not set.
> 2013-11-20 maruel Simplify imports, simplifying pylint checks.
> 2013-11-20 vadimsh@google.com Make stack traces produced by exceptions from TaskChannel.pull() more useful.
> 2013-11-19 maruel Create .isolated files via isolateserver.py archive <directory>.
> 2013-11-19 maruel Move more path handling code from isolate.py into utils/file_path.py.
> 2013-11-18 maruel Add ThreadProolWithProgress.iter_results() support.
> 2013-11-18 maruel Move code around in preparation to move code from isolate.py to isolateserver.py
> 2013-11-12 maruel In r192392, I +x'ed WATCHLISTS by accident. Fix that.
> 2013-11-12 maruel Partially revert 8732761d59. This broke executable bit.
> 2013-11-12 maruel Move read_json and write_json from trace_inputs to utils.tools.
> 2013-11-12 maruel Remove x bit on subprocess32.py, move auto_stub.py into third_party.
> 2013-11-11 maruel Rework swarming.py option grouping to be more sensible.
> 2013-11-11 maruel Enable setting the cache files as read-only.
> 2013-11-11 maruel Make file deletion more coherent with the behavior of each OSes.
> 2013-11-10 maruel Extract subprocess code into subprocess42.
> 2013-11-10 maruel Add test to confirm assumptions about file deletability across different OSes.
> 2013-11-08 maruel Exit the test sooner when it will fail anyway.
> 2013-11-08 maruel Preleminary work to make the file in the run_isolated.py cache read-only.
> 2013-11-08 maruel Fix run_test_case's Popen on Windows once and for all.
> 2013-11-06 maruel Remove support for file mode for symlink.
> 2013-11-06 maruel Fix trace_test_cases_smoke_test.py to stop leaking temp files.
> 2013-11-06 maruel Surface flags more so more settings can be configured at request time.
> 2013-11-06 maruel Remove slave_os as an hardcoded Manifest() dimension.
> 2013-11-06 maruel Make the environment completely configurable in the Manifest.
> 
> R=vadimsh@chromium.org
> 
> Review URL: https://codereview.chromium.org/63523008

TBR=maruel@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=236884

[Ami GONE FROM CHROMIUM, 2013-11-23 00:55:25]

Committed patchset #1 manually as r236884.