@@ -302,20 +302,31 @@ sudo PIP_DOWNLOAD_CACHE=/var/cache/pip pip install `cat $FILES/pips/*`

 # be owned by the installation user, we create the directory and change the

 # ownership to the proper user.

 function git_clone {

-    # if there is an existing checkout, move it out of the way

-    if [[ "$RECLONE" == "yes" ]]; then

-        # FIXME(ja): if we were smarter we could speed up RECLONE by

-        # using the old git repo as the basis of our new clone...

-        if [ -d $2 ]; then

-            mv $2 /tmp/stack.`date +%s`

-        fi

-    fi

-    if [ ! -d $2 ]; then

-        git clone $1 $2

+    GIT_REMOTE=$1

+    GIT_DEST=$2

+    GIT_BRANCH=$3

+

+    # do a full clone only if the directory doesn't exist

+    if [ ! -d $GIT_DEST ]; then

+        git clone $GIT_REMOTE $GIT_DEST

         cd $2

         # This checkout syntax works for both branches and tags

-        git checkout $3

+        git checkout $GIT_BRANCH

+    elif [[ "$RECLONE" == "yes" ]]; then

+        # if it does exist then simulate what clone does if asked to RECLONE

+        cd $GIT_DEST

+        # set the url to pull from and fetch

+        git remote set-url origin $GIT_REMOTE

+        git fetch origin

+        # remove the existing ignored files (like pyc) as they cause breakage

+        # (due to the py files having older timestamps than our pyc, so python

+        # thinks the pyc files are correct using them)

+        sudo git clean -f -d

+        git checkout -f origin/$GIT_BRANCH

+        # a local branch might not exist

+        git branch -D $GIT_BRANCH || true

+        git checkout -b $GIT_BRANCH

     fi

 }