swift-ring-builder blows up when method not found

[Tong Li]

When an invalid method is given, swift-ring-builder will blow up with stack trace.

# swift-ring-builder object.builder balance
Traceback (most recent call last):
  File "/usr/local/bin/swift-ring-builder", line 5, in <module>
    pkg_resources.run_script('swift==1.7.7', 'swift-ring-builder')
  File "build/bdist.linux-x86_64/egg/pkg_resources.py", line 489, in run_script
    yield ep
  File "build/bdist.linux-x86_64/egg/pkg_resources.py", line 1207, in run_script
    def get_metadata(self, name):
  File "/usr/local/lib/python2.7/dist-packages/swift-1.7.7-py2.7.egg/EGG-INFO/scripts/swift-ring-builder", line 673, in <module>
    Commands.__dict__.get(command, Commands.unknown)()
TypeError: unbound method unknown() must be called with Commands instance as first argument (got nothing instead)

Wanted to give rebalance, instead give balance,
swift-ring-builder will show stack trace. it will be nice to catch this error and show a nice error message.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/24549

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/24549
Committed: http://github.com/openstack/swift/commit/b530de2ad55c7ff6982237a9c29219d5cae44742
Submitter: Jenkins
Branch: master

commit b530de2ad55c7ff6982237a9c29219d5cae44742
Author: tong li <email address hidden>
Date: Mon Mar 18 09:04:13 2013 -0400

    swift-ring-builder blows up when not supported command requested.

    swift-ring-builder uses outdated unbounded class method to handle
    not supported command. It worked for python 2.6 or older but not
    for python 2.7 or newer. This patch fixes the problem.

    Change-Id: I7dbc681ef6be44f6d79ff93189ccca13c51eab74
    Fixes: bug #1154882