Unset OS_xx variable before generate configuration

When generate_sample.sh generate the configuration of the
keystone middleware part, it use OS_XXXXX environment variable
if this one is set instead of the default one.

This change unset this vairables, before generate_sample.sh
inspect the code to always have the default value.

Change-Id: I365387e99dff0e1c64cd1c4198088200bf726cd7

tools/conf/generate_sample.sh

@@ -17,6 +17,10 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+
+OS_VARS=$(set | sed -n '/^OS_/s/=[^=*]*$//gp' | xargs)
+[ "$OS_VARS" ] && eval "unset \$OS_VARS"
+
 FILES=$(find ceilometer -type f -name "*.py" ! -path "ceilometer/tests/*" -exec \
     grep -l "Opt(" {} \; | sort -u)