I use the command line:
s3cmd ls s3://somewhere | head
and it reports:

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    An unexpected error has occurred.
  Please report the following lines to:
   s3tools-bugs@lists.sourceforge.net
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Problem: IOError: [Errno 32] Broken pipe
S3cmd:   1.5.0-alpha3

Traceback (most recent call last):
  File "/usr/local/bin/s3cmd", line 2094, in <module>
    main()
  File "/usr/local/bin/s3cmd", line 2034, in main
    cmd_func(args)
  File "/usr/local/bin/s3cmd", line 104, in cmd_ls
    subcmd_bucket_list(s3, uri)
  File "/usr/local/bin/s3cmd", line 162, in subcmd_bucket_list
    "uri": uri.compose_uri(bucket, object["Key"]),
  File "/usr/local/bin/s3cmd", line 37, in output
    sys.stdout.flush()
IOError: [Errno 32] Broken pipe

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    An unexpected error has occurred.
    Please report the above lines to:
   s3tools-bugs@lists.sourceforge.net
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Sincerely,
Muyang Yu
________________________________________________
Muyang Yu
Master Candidate of ECE, Carnegie Mellon University
muyangy@andrew.cmu.edu
muyang.y@gmail.com