After Mark's changes I'm certain that I had a look and the /-notice/Oh! I misunderstood you. Now I see what you mean.
I think what happened is that the Hashtag pages now have both spellings if the feature was used in your group during both intervals of time.
That is, Mark didn't rename the old #wiki into #wiki-notices, he just added the new one internally, and it gets created in the group when used.
At least that's what I see in GMF - There are both spellings in the list/grid view, with the #wiki hashtag listing only the one topic created while it existed, and the #wiki-notice hashtag listing the two that have posted since.
I should probably instantiate all the other new spellings manually, and adjust them all to use the orange color I put on the old ones and have a description. After the dust settles again I can probably alias the old ones out of the list.