cros_workon: only touch local_manifest for minilayout users

Otherwise, you'll duplicate an entry already in the developers
manifest and cause repo to get confused.

BUG=6898
TEST=Verified that local_manifest gets updated when using minilayout.xml
Verified that the local_manifset does not get updated when not.

Change-Id: I67ffc7004a2267d0d5aaa31570ac2bbeaa8f4f96

Review URL: http://codereview.chromium.org/3468009

cros_workon

@@ -136,23 +136,14 @@ show_live_ebuilds () {
   sed -n 's/^[~=]\(.*\)-9999$/\1/p' "${WORKON_FILE}"
 }
 
-find_repo_dir () {
-  curdir=`pwd`
-  while [ $curdir != / ]; do
-    if [ -d "$curdir/.repo" ]; then
-       #echo "Found .repo directory at ${curdir}"
-       REPODIR=${curdir}/.repo
-       return 0
-    fi
-    curdir=`dirname "$curdir"`
-  done
-  echo "Unable to find .repo directory. Did you checkout with repo?"
-  exit 1
-}
-
-
 # This is called only for "cros-workon start". We dont handle the "stop" case since the local changes are ignored anyway since the 9999.ebuild is masked and we dont want to deal with what to do with the user's local changes.
 regen_manifest_and_sync() {
+  # Nothing to do unless you are working on the minilayout
+  local manifest=${CHROOT_TRUNK_DIR}/.repo/manifest.xml
+  if [ $(basename $(readlink -f ${manifest})) != "minilayout.xml" ]; then
+      return
+  fi
+
   for pkgname in $(show_live_ebuilds); do
     eval $(${EBUILDCMD} $(${EQUERYCMD} which ${pkgname}) info)
     local srcdir=$(readlink -m ${CROS_WORKON_SRCDIR})