Extract common functions into a separate file

This is the start of an effort to organize devstack's code
to better document the requirements for configuring the individual
components.

Change-Id: I3476b76b9d1f9ee63687fb9898a98729118cbd84
diff --git a/tools/build_tempest.sh b/tools/build_tempest.sh
index aa44766..230e8f9 100755
--- a/tools/build_tempest.sh
+++ b/tools/build_tempest.sh
@@ -26,7 +26,10 @@
 
 # Keep track of the current directory
 TOOLS_DIR=$(cd $(dirname "$0") && pwd)
-TOP_DIR=`cd $TOOLS_DIR/..; pwd`
+TOP_DIR=$(cd $TOOLS_DIR/..; pwd)
+
+# Import common functions
+. $TOP_DIR/functions
 
 # Abort if localrc is not set
 if [ ! -e $TOP_DIR/localrc ]; then
@@ -43,42 +46,8 @@
 
 TEMPEST_DIR=$DEST/tempest
 
-DIST_NAME=${DIST_NAME:-oneiric}
-
-# git clone only if directory doesn't exist already.  Since ``DEST`` might not
-# be owned by the installation user, we create the directory and change the
-# ownership to the proper user.
-function git_clone {
-
-    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 $GIT_BRANCH
-    elif [[ "$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)
-        find $GIT_DEST -name '*.pyc' -delete
-        git checkout -f origin/$GIT_BRANCH
-        # a local branch might not exist
-        git branch -D $GIT_BRANCH || true
-        git checkout -b $GIT_BRANCH
-    fi
-}
-
 # Install tests and prerequisites
-sudo PIP_DOWNLOAD_CACHE=/var/cache/pip pip install --use-mirrors `cat $TOP_DIR/files/pips/tempest`
+pip_install `cat $TOP_DIR/files/pips/tempest`
 
 git_clone $TEMPEST_REPO $TEMPEST_DIR $TEMPEST_BRANCH