Comment 1 for bug 1424937

This is due to the behaviour of argparse python library used in every python-*client.
I did a test here and argparse is smart enough to figure out what argument you are using based on the prefix of the argument (similar to bash in that if you start typing and hit tab it will figure out which one you are trying to use).
You can test with other clients and see that the same thing happens.

For example:
If you have --verbose and --debug for command you can use
* command --v 1
* command --ver 1
and so on

However, I realized something with cinder list --all-tenants:
There is also a --all_tenants option that apparently does the same thing as --all-tenants. Maybe we could remove that.