Description of problem:"subscription-manager --> pythom-rhsm-->python-dateutil-->six"

Version-Release number of selected component (if applicable):
RHEL6.8

Here is the details from the trace back from subscription-manager core dump.

parser.py:40:<module>:ImportError: No module named six <==== parser.py comes from python-dateutil package 

Traceback (most recent call last):
  File "/usr/libexec/rhsmcertd-worker", line 26, in <module> <===== rhsmcertd-worker comes from subscription-manager
    from rhsm import connection
  File "/usr/lib64/python2.6/site-packages/rhsm/connection.py", line 20, in <module> <==== it calls dateutil.parser 
    import dateutil.parser
  File "/usr/lib/python2.6/site-packages/dateutil/parser.py", line 40, in <module> <========== python-dateutil rpm
    from six import text_type, binary_type, integer_types
ImportError: No module named six