# HG changeset patch
# User Gregory Szorc <gregory.szorc@gmail.com>
# Date 2016-12-26 23:54:33
# Node ID 758526333decf1a16fd0389bf739a786c738dc38
# Parent  9e57033fec0caaf551c285d37f304079587ab570

filemerge: don't use mutable default argument value

diff --git a/mercurial/filemerge.py b/mercurial/filemerge.py
--- a/mercurial/filemerge.py
+++ b/mercurial/filemerge.py
@@ -35,8 +35,8 @@ def _toolstr(ui, tool, part, default="")
 def _toolbool(ui, tool, part, default=False):
     return ui.configbool("merge-tools", tool + "." + part, default)
 
-def _toollist(ui, tool, part, default=[]):
-    return ui.configlist("merge-tools", tool + "." + part, default)
+def _toollist(ui, tool, part, default=None):
+    return ui.configlist("merge-tools", tool + "." + part, default or [])
 
 internals = {}
 # Merge tools to document.