In your Chromium src checkout, try something like 
# touch 1
or 
# touch a

# git status
Untracked files:
  (use "git add <file>..." to include in what will be committed)

	a

Go to third_party/WebKit/, then run
# Tools/Scripts/webkit-patch rebaseline-cl

Expected:
Tool should trigger try jobs

Actual:
Python stacktrace:
Traceback (most recent call last):
  File "Tools/Scripts/webkit-patch", line 84, in <module>
    main()
  File "Tools/Scripts/webkit-patch", line 79, in main
    WebKitPatch(os.path.abspath(__file__)).main()
  File "/usr/local/google/home/drott/dev/blink/src/third_party/WebKit/Tools/Scripts/webkitpy/tool/webkit_patch.py", line 124, in main
    result = command.check_arguments_and_execute(options, args, self)
  File "/usr/local/google/home/drott/dev/blink/src/third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/command.py", line 110, in check_arguments_and_execute
    return self.execute(options, args, tool) or 0
  File "/usr/local/google/home/drott/dev/blink/src/third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_cl.py", line 56, in execute
    unstaged_baselines = self.unstaged_baselines()
  File "/usr/local/google/home/drott/dev/blink/src/third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline.py", line 532, in unstaged_baselines
    unstaged_changes = self._tool.git().unstaged_changes()
  File "/usr/local/google/home/drott/dev/blink/src/third_party/WebKit/Tools/Scripts/webkitpy/common/checkout/git.py", line 171, in unstaged_changes
    assert len(line) > 4, 'Unexpected change line format %s' % line
AssertionError: Unexpected change line format ?? a


Probably the regexp in unstaged_baselines() of rebaseline.py should be adjusted:
        baseline_re = re.compile(r'.*[\\/]LayoutTests[\\/].*-expected\.(txt|png|wav)$')