When running bisect-builds.py I get the following error:

nasko@atomic:~/chromium/src$ ./tools/bisect-builds.py                                                                                                                    
  File "./tools/bisect-builds.py", line 897
    return m.group(1)]
                     ^
SyntaxError: invalid syntax

Looking at history of the file, it looks like revision 404742 is to be blamed.

commit 08c596825aa5530f6364e59ecff7a8ac1323f9b8
Author: Di Mu <dimu@chromium.org>
Date:   Mon Jul 11 16:05:07 2016 -0700

    Stop reading svn buildspec
    
    Review URL: https://codereview.chromium.org/2136353002 .
    Cr-Commit-Position: refs/heads/master@{#404742}

...
-      return m.group(1)
+      return m.group(1)]
...

Therefore assigning it to dimu@, so it can be resolved. A simple removal of the extra "]" seems to fix it for me.