split: check unfinished first

Differential Revision: https://phab.mercurial-scm.org/D161

hgext3rd/fbamend/split.py

@@ -60,6 +60,7 @@ def split(ui, repo, *revs, **opts):
         wlock = repo.wlock()
         lock = repo.lock()
         cmdutil.bailifchanged(repo)
+        cmdutil.checkunfinished(repo)
         tr = repo.transaction('split')
         ctx = repo[rev]
         r = ctx.rev()