@@ -222,6 +222,30 @@ GetOSVersion() {

     export os_VENDOR os_RELEASE os_UPDATE os_PACKAGE os_CODENAME

 }

+# git update using reference as a branch.

+function git_update_branch() {

+

+    GIT_BRANCH=$1

+

+    git checkout -f origin/$GIT_BRANCH

+    # a local branch might not exist

+    git branch -D $GIT_BRANCH || true

+    git checkout -b $GIT_BRANCH

+}

+

+

+# git update using reference as a tag. Be careful editing source at that repo

+# as working copy will be in a detached mode

+function git_update_tag() {

+

+    GIT_TAG=$1

+

+    git tag -d $GIT_TAG

+    # fetching given tag only

+    git fetch origin tag $GIT_TAG

+    git checkout -f $GIT_TAG

+}

+

 # 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

@@ -235,16 +259,16 @@ function git_clone {

     GIT_REMOTE=$1

     GIT_DEST=$2

-    GIT_BRANCH=$3

+    GIT_REF=$3

-    if echo $GIT_BRANCH | egrep -q "^refs"; then

+    if echo $GIT_REF | egrep -q "^refs"; then

         # If our branch name is a gerrit style refs/changes/...

         if [[ ! -d $GIT_DEST ]]; then

             [[ "$ERROR_ON_CLONE" = "True" ]] && exit 1

             git clone $GIT_REMOTE $GIT_DEST

         fi

         cd $GIT_DEST

-        git fetch $GIT_REMOTE $GIT_BRANCH && git checkout FETCH_HEAD

+        git fetch $GIT_REMOTE $GIT_REF && git checkout FETCH_HEAD

     else

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

         if [[ ! -d $GIT_DEST ]]; then

@@ -252,7 +276,7 @@ function git_clone {

             git clone $GIT_REMOTE $GIT_DEST

             cd $GIT_DEST

             # This checkout syntax works for both branches and tags

-            git checkout $GIT_BRANCH

+            git checkout $GIT_REF

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

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

             cd $GIT_DEST

@@ -263,10 +287,17 @@ function git_clone {

             # (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

+

+            # handle GIT_REF accordingly to type (tag, branch)

+            if [[ -n "`git show-ref refs/tags/$GIT_REF`" ]]; then

+                git_update_tag $GIT_REF

+            elif [[ -n "`git show-ref refs/heads/$GIT_REF`" ]]; then

+                git_update_branch $GIT_REF

+            else

+                echo $GIT_REF is neither branch nor tag

+                exit 1

+            fi

+

         fi

     fi

 }