Skip creating new repo versions when content has not changed
Per our discussion on pulp-dev, we should stop creating new repo versions if content has not changed. To recap the reasons:
- They were meant to serve as a historical record but this information is available by looking at the tasks api
- It creates additional, unnecessary versions and bumps the latest version number of the repo
- If we ever have a feature to retain only the latest X repo versions, it'll be less useful since some repo versions may not have any changes
I believe sync is the only place that needs to be updated but we may also need to consider any other places in the code.
Also, we should document that this is the intended behavior.