Lots of people who want to add Facebook pages of the form /pages/BlahBlahBlah/123456789 remove the digits from the end, which breaks the URL. It would be nice if we could catch these and tell people the URL won't work.
See for example http://musicbrainz.org/edit/14880236 and http://musicbrainz.org/edit/15364368
I guess the regex it needs to match (when the path starts with /pages/, that is) is /pages/[^/]+/[0-9]+
In review with http://codereview.musicbrainz.org/r/1816/