Hello,
After much discussion on the pull request
<https://github.com/gentoo/gentoo/pull/7274>, reviewers and I have
concluded with a new pkg_pretend message, which I would like to use as
the new news message as well. As before, I ask that the committer of
that merge request adjust the posted date in this news item and add it
to the news repo when accepting the PR. Thanks!

Title: Radicale 2 requires pre-install migration
Author: Christopher Head <chead@chead.ca>
Posted: 2018-03-30
Revision: 2
News-Item-Format: 2.0
Display-If-Installed: <www-apps/radicale-2

Radicale version 2 uses a new storage format and is not able to read
databases created by version 1. Version 1 releases starting from 1.1.3
include a --export-storage option which can be used to export their
databases in a format that Radicale 2 can use; you must do this before
upgrading to version 2.

If you have kept the Gentoo-default database configuration, this will
work:
1. Stop any running instance of Radicale.
2. Run `radicale --export-storage ~/radicale-exported`.
3. Run `chown -R radicale: ~/radicale-exported`
4. Run `mv /var/lib/radicale /var/lib/radicale.old`.
5. Install Radicale version 2.
6. Run `mv ~/radicale-exported /var/lib/radicale/collections`.

For more details, or if you are have a more complex configuration,
please see the migration guide: http://radicale.org/1to2/
If you do a custom migration, please ensure the database is cleaned out
of /var/lib/radicale, including the hidden .props file.
-- 
Christopher Head