--- a/mercurial/dispatch.py	Sun Mar 19 00:18:53 2017 -0400
+++ b/mercurial/dispatch.py	Sun Mar 19 00:21:26 2017 -0400
@@ -92,8 +92,13 @@
     if inst.hint:
         write(_("(%s)\n") % inst.hint)
 
+def _mayberepr(a):
+    if ' ' in a:
+        return repr(a)
+    return a
+
 def _formatargs(args):
-    return ' '.join(' ' in a and repr(a) or a for a in args)
+    return ' '.join(_mayberepr(a) for a in args)
 
 def dispatch(req):
     "run the command specified in req.args"