HBASE-21999 [DEBUG] Exit if git returns empty revision!

hbase-common/src/saveVersion.sh

@@ -18,6 +18,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+set -e
+
 unset LANG
 unset LC_CTYPE
 
@@ -45,10 +47,12 @@ else
   revision="Unknown"
   url="file://$cwd"
 fi
-which md5sum > /dev/null
-if [ "$?" != "0" ] ; then
-  which md5 > /dev/null
-  if [ "$?" != "0" ] ; then
+if [ -z $revision ]; then
+  echo "$revision is empty!"
+  exit 1
+fi
+if ! [  -x "$(command -v md5sum)" ]; then
+  if ! [ -x "$(command -v md5)" ]; then
     srcChecksum="Unknown"
   else
     srcChecksum=`find hbase-*/src/main/ | grep -e "\.java" -e "\.proto" | LC_ALL=C sort | xargs md5 | md5 | cut -d ' ' -f 1`