From 555507975dd8fda3d7490d9d23219fc2d6928306 Mon Sep 17 00:00:00 2001
From: Thomas Nagy <tnagy@waf.io>
Date: Sat, 19 Mar 2016 10:26:42 +0100
Subject: [PATCH] Rewrite ConfigSet._get_list_value_for_modification

---
 README.md           |  2 +-
 waflib/ConfigSet.py | 18 +++++++++++-------
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/README.md b/README.md
index 653ec8c0..b6ff9eca 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ Download the project from our page on [waf.io](https://waf.io/) or from the mirr
 
 ## HOW TO CREATE THE WAF SCRIPT
 
-Python >= 2.6 3.4 is required to generate the waf script, and the resulting file can then run on Python 2.5.
+Python >= 2.6 is required to generate the waf script, and the resulting file can then run on Python 2.5.
 Just execute:
 ```sh
 $ ./waf-light configure build
diff --git a/waflib/ConfigSet.py b/waflib/ConfigSet.py
index fc5c9002..2d6aae20 100644
--- a/waflib/ConfigSet.py
+++ b/waflib/ConfigSet.py
@@ -191,16 +191,20 @@ class ConfigSet(object):
 		try:
 			value = self.table[key]
 		except KeyError:
-			try: value = self.parent[key]
-			except AttributeError: value = []
-			if isinstance(value, list):
-				value = value[:]
+			try:
+				value = self.parent[key]
+			except AttributeError:
+				value = []
 			else:
-				value = [value]
+				if isinstance(value, list):
+					# force a copy
+					value = value[:]
+				else:
+					value = [value]
+			self.table[key] = value
 		else:
 			if not isinstance(value, list):
-				value = [value]
-		self.table[key] = value
+				self.table[key] = value = [value]
 		return value
 
 	def append_value(self, var, val):