It appears that if the copyright date on the ChangeLog is wrong, repoman doesn't add commit messages to it. An example of this behavior can be seen in the commits to kde-misc/kover over the past couple of days. Portage version 2.2.0_alpha155.
I've looked at the diffs and the only change I see is 2012 -> 2013. Is that what you think caused it? Do you think it's reproducible? Nobody else has reported problems with the 2012 -> 2013 transition.
I don't know if it's reproducible, this is the only time I've seen it happen. In the commit that fixed kover-5 and added kover-6, as well as the commit that removed kover-5, it appears that ChangeLog was not touched at all, and then when I manually changed the date and committed that, the next update properly modified ChangeLog. That's why I think it was the date, but I haven't seen the problems in my other 2012-2013 commits as well so I really don't know for sure.
I suspect what happened is that the timestamp of ChangeLog differed from the value recorded in CVS/Entries. You can avoid this by doing `cvs up ChangeLog`, which causes cvs to sync the timestamp value in CVS/Entries.
To clarify the reason for the behavior, repoman thinks you've modified the ChangeLog when the timestamp differs from the value in CVS/Entries. In this case, repoman skips ChangeLog generation, since it assumes you already called echangelog or something.
With Gentoo finally moved to a git based tree, the CVS and Changelog code are not likely to be used together. In fact It will be difficult to check all the CVS code in the rewrite currently under way. Re-open if it still does apply
