Imported using git-ubuntu import.
Changelog parent: 0d33db8e8f8e44ee087f8d3de7ccd59539f580ec
New changelog entries:
* The EXTRA_ARCHIVES environment variable defined in 2.212 doesn't quite
work properly because it doesn't allow for signing key configuration.
Rename it to the more domain-specific EXTRA_PPAS (which is now a
space-separated sequence of <ppa-owner>/<ppa-name> pairs), and fetch
signing keys for those from Launchpad using python3-software-properties.
