[makeotf] Enable output to be folder only?

[frankrolf]

makeotf -o my_folder/ fails with

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/site-packages/afdko/Tools/SharedData/FDKScripts/MakeOTF.py", line 2627, in main
    runMakeOTF(makeOTFParams)
  File "/usr/local/lib/python2.7/site-packages/afdko/Tools/SharedData/FDKScripts/MakeOTF.py", line 2365, in runMakeOTF
    os.remove(outputPath)
OSError: [Errno 1] Operation not permitted: 'my_folder'
Done.

It would be a nice feature to pass a folder only to the -o option, to generate the OTF with standard file name within that folder.