diff --git a/mercurial/patch.py b/mercurial/patch.py
--- a/mercurial/patch.py
+++ b/mercurial/patch.py
@@ -1199,7 +1199,7 @@ def iterhunks(fp):
             m = gitre.match(x)
             if not m:
                 continue
-            if gitpatches is None:
+            if not gitpatches:
                 # scan whole input for git metadata
                 gitpatches = [('a/' + gp.path, 'b/' + gp.path, gp) for gp
                               in scangitpatch(lr, x)]
diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -667,9 +667,9 @@ class ui(object):
         printed.'''
         if self.tracebackflag:
             if exc:
-                traceback.print_exception(exc[0], exc[1], exc[2])
+                traceback.print_exception(exc[0], exc[1], exc[2], file=self.ferr)
             else:
-                traceback.print_exc()
+                traceback.print_exc(file=self.ferr)
         return self.tracebackflag
 
     def geteditor(self):
diff --git a/tests/test-setdiscovery.t b/tests/test-setdiscovery.t
--- a/tests/test-setdiscovery.t
+++ b/tests/test-setdiscovery.t
@@ -288,7 +288,7 @@ One with >200 heads, which used to use u
   reading DAG from stdin
 
   $ hg heads -t --template . | wc -c
-  261
+   *261 (re)
 
   $ hg clone -b a . a
   adding changesets