git new-branch displays an explanatory line.

BUG=

Review URL: https://codereview.chromium.org/253013004

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@266905 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/subprocess2.py b/subprocess2.py
index 716ef20..3beeaeb 100644
--- a/subprocess2.py
+++ b/subprocess2.py
@@ -510,5 +510,5 @@
   """
   kwargs.setdefault('stdin', VOID)
   if 'stdout' in kwargs:
-    raise ValueError('stdout argument not allowed, it will be overridden.')
+    raise ValueError('stdout argument not allowed, it would be overridden.')
   return check_call_out(args, stdout=PIPE, **kwargs)[0]