restart_in_chroot_if_needed can run scripts from bin/. cros_workon_now does this

BUG=chromium-os:9877
TEST=ran bin/cros_workon_now, cros_workon, set_shared_user_password

Note---this introduces another bashism to common.sh.  However, despite
comments to the contrary, common.sh does not actually parse under dash
without this change

Change-Id: I1e6b9751afa8341c100f3b8e0b96284835a53d17

Review URL: http://codereview.chromium.org/5444002

bin/cros_workon_make

@@ -10,7 +10,7 @@
 . "$(dirname $0)/../common.sh"
 
 # Script must be run inside the chroot.
-assert_inside_chroot
+restart_in_chroot_if_needed "$@"
 
 get_default_board
 

common.sh

@@ -106,7 +106,7 @@ DEFAULT_BUILD_ROOT=${CHROMEOS_BUILD_ROOT:-"$SRC_ROOT/build"}
 # Set up a global ALL_BOARDS value
 if [ -d $SRC_ROOT/overlays ]; then
   ALL_BOARDS=$(cd $SRC_ROOT/overlays;ls -1d overlay-* 2>&-|sed 's,overlay-,,g')
-fi 
+fi
 # Strip CR
 ALL_BOARDS=$(echo $ALL_BOARDS)
 # Set a default BOARD
@@ -231,11 +231,15 @@ function make_pkg_common {
 
 # Enter a chroot and restart the current script if needed
 function restart_in_chroot_if_needed {
+  # NB:  Pass in ARGV:  restart_in_chroot_if_needed "$@"
   if [ $INSIDE_CHROOT -ne 1 ]
   then
-    # Equivalent to enter_chroot.sh -- <current command>
+    local abspath=$(readlink -f "$0")
+    # strip everything up to (and including) /src/scripts/ from abspath
+    local path_from_scripts="${abspath##*/src/scripts/}"
     exec $SCRIPTS_DIR/enter_chroot.sh -- \
-      $CHROOT_TRUNK_DIR/src/scripts/$(basename $0) $*
+      "$CHROOT_TRUNK_DIR/src/scripts/$path_from_scripts" "$@"
+    exit
   fi
 }