# HG changeset patch
# User Yuya Nishihara <yuya@tcha.org>
# Date 1476803147 -32400
# Node ID 0f81ed8e147b60b939dd4580c05f31a1aa464a16
# Parent  cdb5a320d2bf815800f2f214b336c046cb4cdd8d
util: drop mutable default from popen()

It can be None because it is used only if not empty.

diff -r cdb5a320d2bf -r 0f81ed8e147b hglib/util.py
--- a/hglib/util.py	Wed Oct 19 00:03:44 2016 +0900
+++ b/hglib/util.py	Wed Oct 19 00:05:47 2016 +0900
@@ -206,7 +206,7 @@
     startupinfo = subprocess.STARTUPINFO()
     startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
 
-def popen(args, env={}):
+def popen(args, env=None):
     environ = None
     if env:
         environ = dict(os.environ)