Give precedence to trusty-updates in trusty sysroot

build/linux/sysroot_scripts/merge-package-lists.py

+#!/usr/bin/env python
+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Merge package entries from different package lists.
+"""
+
+# This is used for replacing packages in eg. trusty with those in
+# trusty-updates.  The updated packages are ABI compatible, but
+# include security patches, so we should use those instead in our
+# sysroots.
+
+import sys
+
+if len(sys.argv) != 2:
+  exit(1)
+
+packages = {}
+
+def AddPackagesFromFile(file):
+  global packages
+  lines = file.readlines()
+  if len(lines) % 3 != 0:
+    exit(1)
+  for i in xrange(0, len(lines), 3):
+    packages[lines[i]] = (lines[i + 1], lines[i + 2])
+
+AddPackagesFromFile(open(sys.argv[1], 'r'))
+AddPackagesFromFile(sys.stdin)
+
+output_file = open(sys.argv[1], 'w')
+
+for (package, (filename, sha256)) in packages.iteritems():
+  output_file.write(package + filename + sha256)