I edited http://musicbrainz.org/release/e885399a-3bfe-4e63-8418-0661d24f7353 in the RE and added " " (four spaces) in the join phrase of the first track's AC.
Now see the AC for track 1 here: http://musicbrainz.org/ws/2/release/e885399a-3bfe-4e63-8418-0661d24f7353?inc=recordings+artist-credits which has a joinphrase of " " for the last/only name credit.
There are probably a good amount of ACs with this useless whitespace because http://userscripts.org/scripts/show/117663 had a bug that caused it to be added. It should be removed by the RE and the server.
That release no longer exists – can you provide an alternate example?
Here's a new example:
Same exact steps apply.
This will be impossible with MBS-5182, so I'm closing this as fixed.