Comment 14 for bug 1628279

@rlaager
@kirkland
@happyaron

The SRU are usally for "High-impact bugs"... but the current SRU for Xenial might possibly fit in section :

2. When
2.2. Other safe cases

For Long Term Support releases we sometimes want to introduce new features. They must not change the behaviour on existing installations (e. g. entirely new packages are usually fine). If existing software needs to be modified to make use of the new feature, it must be demonstrated that these changes are unintrusive, have a minimal regression potential, and have been tested properly. To avoid regressions on upgrade, any such feature must then also be added to any newer supported Ubuntu release. Once a new feature/package has been introduced, subsequent changes to it are subject to the usual requirements of SRUs to avoid regressions.

[1] - https://wiki.ubuntu.com/StableReleaseUpdates

Eric