diff -r 11c253997b0e -r 7beb3ec34443 mercurial/hg.py
--- a/mercurial/hg.py	Mon Feb 13 11:32:09 2017 -0800
+++ b/mercurial/hg.py	Mon Feb 13 11:58:02 2017 -0800
@@ -739,6 +739,8 @@
         if clean:
             ret = _clean(repo, checkout)
         else:
+            if check:
+                cmdutil.bailifchanged(repo, merge=False)
             ret = _update(repo, checkout)
 
         if not ret and movemarkfrom: