Roll tools/swarming_client/ to b39a448d8522392389b28f6997126a6ab04bfe87.

$ git log f222001cc..b39a448d8 --date=short --format='%ad %ae %s' | sed 's/@chromium\.org//'
2015-05-11 maruel Fix crash when exit_code=='N/A'.
2015-05-04 maruel Handle SIGTERM while uploading results back.
2015-04-27 phajdan.jr Don't use parent of root_dir as temp directory
2015-04-22 maruel Trap TypeError in collect when trigger had failed.

R=vadimsh@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1131013003

Cr-Commit-Position: refs/heads/master@{#329321}

DEPS

@@ -54,7 +54,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling swarming_client
   # and whatever else without interference from each other.
-  'swarming_revision': 'f222001cc23c7cdb574bf4cfb447f65c94bc6da3',
+  'swarming_revision': 'b39a448d8522392389b28f6997126a6ab04bfe87',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
   # and whatever else without interference from each other.