don't rename empty ids to non-empty ones
don't rename empty ids to non-empty ones

darcs-hash:20060420051218-1a7c6-b96c0a6998c3a5fdd9f659a3d4dd0ddc8a1e448d

kirbyfan64/jhc,kirbyfan64/jhc,kirbyfan64/jhc,kirbyfan64/jhc