diff -r ad074f900907 -r cb759f7f940d mercurial/ui.py
--- a/mercurial/ui.py	Mon Feb 20 12:31:39 2017 +0100
+++ b/mercurial/ui.py	Fri Feb 24 19:28:45 2017 +0100
@@ -822,9 +822,9 @@
 
     def write_err(self, *args, **opts):
         self._progclear()
+        if self._bufferstates and self._bufferstates[-1][0]:
+            return self.write(*args, **opts)
         try:
-            if self._bufferstates and self._bufferstates[-1][0]:
-                return self.write(*args, **opts)
             with self.timeblockedsection('stdio'):
                 if not getattr(self.fout, 'closed', False):
                     self.fout.flush()