Why redhat-support-tool failed to upload a file to dropbox

Issue

• I used the redhat-support-tool command to upload a file to Red Hat FTP server (dropbox.redhat.com) described in https://access.redhat.com/solutions/2112
• I failed with the following error.

XXXX-XX-XX XX:XX:XX,XXX - redhat_support_tool.plugins.add_attachment - ERROR - ERROR: Problem encountered whilst uploading the attachment.  Please consult the Red Hat Support Tool 
logs for details.
XXXX-XX-XX XX:XX:XX,XXX - redhat_support_tool.helpers.launchhelper - ERROR - local variable 'timer' referenced before assignment
Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/redhat_support_tool/helpers/launchhelper.py", line 106, in run
    return cls.non_interactive_action()
  File "/usr/lib/python2.6/site-packages/redhat_support_tool/plugins/add_attachment.py", line 437, in non_interactive_action
    useFtp=self.use_ftp)
  File "/usr/lib/python2.6/site-packages/redhat_support_lib/infrastructure/brokers.py", line 612, in add
    amnt = FtpHelper.ftp_attachment(fileName, caseNumber, fileChunk)
  File "/usr/lib/python2.6/site-packages/redhat_support_lib/utils/ftphelper.py", line 135, in ftp_attachment
    timer.stop()
UnboundLocalError: local variable 'timer' referenced before assignment