This originally contained a change to fix src component detection. This was moved to a separate review now (D21579) to speed up review of the bugfix and allow a separate commit that could be MFCed.
While debugging the issue mentioned above, I added a showconfig command which I found useful enough to leave it in and document it in the man page.
Like discussed somewhere else, I also added an updatesready command that can be used to check if there are any pending fetched updates that can be installed. It exits on status code 2 in case there aren't any pending updates so that if one can tell apart exit 1 (=error) from it (right now there is no code path for that, but if more checks are added in the future this could be useful).
Finally, I changed the exit code of freebsd-update install in case there are no updates pending to be installed and there wasn't a fetch phase to 2 - this should allow future scripts to differentiate between "error" and "nothing to be done" without breaking existing jail managers like ezjail and iocell.
Besides documentation changed, I also added a comma in the manpage to pacify igor.
Happy to accept naming changes (like, if the reviewers happen to not like updatesready and showconfig). Feel free to correct my English.
See also:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=239997
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=240177