How to release pytest

Important

pytest releases must be prepared on Linux because the docs and examples expect to be executed in that platform.

Install development dependencies in a virtual environment with:
```
pip3 install -r tasks/requirements.txt
```
Create a branch release-X.Y.Z with the version for the release.
- patch releases: from the latest master;
- minor releases: from the latest features; then merge with the latest master;
Ensure your are in a clean work tree.
Generate docs, changelog, announcements and upload a package to your devpi staging server:
```
invoke generate.pre_release <VERSION> <DEVPI USER> --password <DEVPI PASSWORD>
```
If --password is not given, it is assumed the user is already logged in devpi. If you don't have an account, please ask for one.
Open a PR for this branch targeting master.
Test the package
- Manual method
  
  Run from multiple machines:
```
devpi use https://devpi.net/USER/dev
devpi test pytest==VERSION
```
  Check that tests pass for relevant combinations with:
```
devpi list pytest
```
- CI servers
  
  Configure a repository as per-instructions on devpi-cloud-test to test the package on Travis and AppVeyor. All test environments should pass.
Publish to PyPI:
```
invoke generate.publish_release <VERSION> <DEVPI USER> <PYPI_NAME>
```
where PYPI_NAME is the name of pypi.python.org as configured in your ~/.pypirc file for devpi.
After a minor/major release, merge features into master and push (or open a PR).

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