Description of problem:
If a user creates a changeset and goes through the motions, that changeset is saved in changeset history. However, from that point on, the name of this changeset is unique and can never be used again.  

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


How reproducible:


Steps to Reproduce:
1.  Create a new changeset called 'PushToDev' and add packages to it
2.  Promote this changeset
3.  Navigate to Changeset History; note the existence of your "PushToDev" changeset in the audit.
4.  Attempt to create a new changeset, also called 'PushToDev'
5.  Attempt to promote this changeset

Actual results:
Validation Failed:
Name Must be unique within an environment

Expected results:
Completed/archived Changesets should be stored with something else as the unique key, as to allow users to re-use names over and over again.  While namespace is basically infinite, it's evident that users can very quickly run out of 'convenient' namespace.

I'm also not sure why users are able to change Names (and possibly descriptions) in an apparently-archived Changset History audit trail, but that might be a different bug.

Additional info: