git tag -l requires pwd==GERRIT_PROJECT so pushd/popd as needed

Change-Id: I0cef0119e1ee62f303da930216980f038ece5f78
diff --git a/jjb/shell/github-release.sh b/jjb/shell/github-release.sh
index 31c54b7..ee95292 100755
--- a/jjb/shell/github-release.sh
+++ b/jjb/shell/github-release.sh
@@ -276,7 +276,10 @@
         get_version __ver
 
     elif [[ -v WORKSPACE ]] && [[ -v GITHUB_TOKEN ]]; then # i_am_jenkins
+	declare -p GERRIT_PROJECT
+	pushd "$GERRIT_PROJECT" || error "pushd GERRIT_PROJECT= failed"
         __ver="$(git tag -l --points-at HEAD)"
+	popd "$GERRIT_PROJECT" || error "popd GERRIT_PROJECT= failed"
 
     elif [[ -v argv_version_file ]]; then # local debug
         [[ ! -f VERSION ]] && error "./VERSION file not found"
@@ -284,7 +287,10 @@
         __ver="v${tmp[0]}"
 
     else
+	declare -p GERRIT_PROJECT
+	pushd "$GERRIT_PROJECT" || error "pushd GERRIT_PROJECT= failed"
         __ver="$(git tag -l --points-at HEAD)"
+	popd "$GERRIT_PROJECT" || error "popd GERRIT_PROJECT= failed"
     fi
 
     # ------------------------------------------------------