This transition is from git-annex sync needing --content to send content to repositories that have preferred content configured, to sending content by default to such repositories.

There should be no change in behavior with repositories that don't have preferred content configured. sync without --content won't populate them since that would be a surprising thing and a warning based transition was judged by the community to be not sufficient to avoid that possible large surprise. (See ?Changing sync to include content breaks UX)

A warning was added in August 2023 when it's run in a way that will change behavior. It would be good to wait until all git-annex users have gotten the version with the warning, and used it for a while, before finishing the transition.

Using the August 2025 debian stable release that included the warning as the start point, I suggest September 2026 as the transition end date. --Joey

Now thinking I can avoid waiting that long, especially since the pending release has some pull/push drop behavior changes that would be well bundled with this change.

Users who upgraded to Debian stable last September will have gotten 8 months of warnings. And they will mostly not be upgrading to a new version of Debian until the next stable release, which will be in 2027. While some may choose to upgrade git-annex, there is not currently a backport so they would have to install eg linuxstandalone.

(Users of other distributions are on other schedules, but I generally take Debian stable as a benchmark of fairly slow updating users. And the timing of the warning being added right after the previous Debian stable release makes debian stable pretty much worst case for the timing of this.) --Joey