Always use our dpkg wrapper when mastering an image.

src/package_scripts/base-files.postinst

Index: src/package_scripts/base-files.postinst
diff --git a/src/package_scripts/base-files.postinst b/src/package_scripts/base-files.postinst
new file mode 100755
index 0000000000000000000000000000000000000000..c07ce307d0271375e58f758602b7b9f7edab0b94
--- /dev/null
+++ b/src/package_scripts/base-files.postinst
@@ -0,0 +1,18 @@
+#!/bin/bash
+
+# Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# base-files
+
+cp -a "${ROOT}/usr/share/base-files/networks"  \
+  "${ROOT}/usr/share/base-files/nsswitch.conf" \
+  "${ROOT}/usr/share/base-files/profile"       \
+  "${ROOT}/etc/"
+
+# TODO: Does this belong here or in another postinst?
+touch "${ROOT}/etc/fstab"
+
+# TODO:This is needed by stuff that uses sysv-rc. Maybe move there?
+mkdir -p "${ROOT_FS_DIR}/etc/init.d"