Copy the netrc into the chroot at entry.

This seems to be needed for acessing some of the chrome repositories.
Without it we get git clone hangs trying to sync.

BUG=chromium-os:38303
TEST=local entry into chroot

Change-Id: Ia68a6486022e8d230572bad0f9031c3e5d36197c
Previous-Reviewed-on: https://gerrit.chromium.org/gerrit/42140
(cherry picked from commit 45ebc4c9fc9cbf0af91773e4553ea8475d18cedb)
Reviewed-on: https://gerrit.chromium.org/gerrit/46147
Reviewed-by: Dave Parker <dparker@chromium.org>
Tested-by: Peter Mayo <petermayo@chromium.org>
Commit-Queue: Dave Parker <dparker@chromium.org>
diff --git a/sdk_lib/enter_chroot.sh b/sdk_lib/enter_chroot.sh
index c81f89f..04c9147 100755
--- a/sdk_lib/enter_chroot.sh
+++ b/sdk_lib/enter_chroot.sh
@@ -85,6 +85,7 @@
   .gdata_cred.txt             # User/password for Google Docs on chromium.org
   .gdata_token                # Auth token for Google Docs on chromium.org
   .disable_build_stats_upload # Presence of file disables command stats upload
+  .netrc                      # May contain required source fetching credentials
 )
 
 INNER_CHROME_ROOT=$FLAGS_chrome_root_mount  # inside chroot