Releasing New Rez Versions

To merge a PR to master and release a new version:

Merge the PR locally, following the instructions given on GitHub in the command line instructions link (but do not push to master yet);
Run the tests (rez-selftest) to double check nothing is broken;
Make sure the rez version is correct, and change if necessary. The version may have been correct at the time of PR submission, but may need an update due to releases that have occurred since;
Update the changelog. A handy utility is provided to help you do this. To use it, run the following command, replacing X, Y, Z etc with all pull request and issue numbers associated with the release:
```
]$ python ./release-rez.py -c X Y Z
```
This command prints the changelog entry to stdout, which you can then paste in to the top of CHANGELOG.md.
Run the release-rez utility script. This performs the following actions:
- Pushes codebase to master;
- Creates tag on latest version, and pushes tag to master;
- Generates the new GitHub release (https://github.com/nerdvegas/rez/releases).
```
]$ python ./release-rez.py
```
Relax.

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