I've been changing a few thousand ways (removing unused tag). I did the upload in 500 way chunks with JOSM, but because it took too long (and too much memory), I've killed JOSM. Now I've produced an unfinished changeset. How can I close it?

I've been changing a few thousand ways (removing unused tag). I did the upload in 500 way chunks with JOSM, but because it took too long (and too much memory), I've killed JOSM. Now I've produced an unfinished changeset. How can I close it?