[autobisectjs] After .busted file goes onto S3, a subsequent bisection using "-l bad" throws

[nth10sd]

Rev b75561ff5ffe: Finished downloading.
Traceback (most recent call last):
  File "/usr/lib/python3.6/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.6/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/home/ubuntu/.local/lib/python3.6/site-packages/funfuzz/autobisectjs/__main__.py", line 13, in <module>
    main()
  File "/home/ubuntu/.local/lib/python3.6/site-packages/funfuzz/autobisectjs/autobisectjs.py", line 540, in main
    findBlamedCset(options, repo_dir, compile_shell.makeTestRev(options))
  File "/home/ubuntu/.local/lib/python3.6/site-packages/funfuzz/autobisectjs/autobisectjs.py", line 243, in findBlamedCset
    label = testRev(currRev)
  File "/home/ubuntu/.local/lib/python3.6/site-packages/funfuzz/js/compile_shell.py", line 618, in testRev
    obtainShell(shell, updateToRev=rev)
  File "/home/ubuntu/.local/lib/python3.6/site-packages/funfuzz/js/compile_shell.py", line 656, in obtainShell
    raise Exception("Found a .busted file for rev " + shell.get_hg_hash())
Exception: Found a .busted file for rev b75561ff5ffe

A workaround is to first remove the corresponding .busted file on S3, clearing the corresponding directory in local shell-cache before re-running in -l bad mode.