Provider network subnets based on IP version

Subnets for both IP version 4 and 6 are created even if IP_VERSION is set to 4.
Added two if statements to only create subnets that are nessesary.

Change-Id: I87c97741808726a260c846db48c10931e8991a74
diff --git a/lib/neutron b/lib/neutron
index 3c6b0db..954a2d9 100755
--- a/lib/neutron
+++ b/lib/neutron
@@ -538,8 +538,15 @@
         die_if_not_set $LINENO PHYSICAL_NETWORK "You must specify the PHYSICAL_NETWORK"
         die_if_not_set $LINENO PROVIDER_NETWORK_TYPE "You must specifiy the PROVIDER_NETWORK_TYPE"
         NET_ID=$(neutron net-create $PHYSICAL_NETWORK --tenant_id $TENANT_ID --provider:network_type $PROVIDER_NETWORK_TYPE --provider:physical_network "$PHYSICAL_NETWORK" ${SEGMENTATION_ID:+--provider:segmentation_id $SEGMENTATION_ID} --shared | grep ' id ' | get_field 2)
-        SUBNET_ID=$(neutron subnet-create --tenant_id $TENANT_ID --ip_version 4 ${ALLOCATION_POOL:+--allocation-pool $ALLOCATION_POOL} --name $PROVIDER_SUBNET_NAME --gateway $NETWORK_GATEWAY $NET_ID $FIXED_RANGE | grep ' id ' | get_field 2)
-        SUBNET_V6_ID=$(neutron subnet-create --tenant_id $TENANT_ID --ip_version 6 --ipv6-address-mode slaac --gateway $V6_NETWORK_GATEWAY --name $PROVIDER_SUBNET_NAME_V6 $NET_ID $FIXED_RANGE_V6 | grep 'id' | get_field 2)
+
+        if [[ "$IP_VERSION" =~ 4.* ]]; then
+            SUBNET_ID=$(neutron subnet-create --tenant_id $TENANT_ID --ip_version 4 ${ALLOCATION_POOL:+--allocation-pool $ALLOCATION_POOL} --name $PROVIDER_SUBNET_NAME --gateway $NETWORK_GATEWAY $NET_ID $FIXED_RANGE | grep ' id ' | get_field 2)
+        fi
+
+        if [[ "$IP_VERSION" =~ .*6 ]]; then
+            SUBNET_V6_ID=$(neutron subnet-create --tenant_id $TENANT_ID --ip_version 6 --ipv6-address-mode slaac --gateway $V6_NETWORK_GATEWAY --name $PROVIDER_SUBNET_NAME_V6 $NET_ID $FIXED_RANGE_V6 | grep 'id' | get_field 2)
+        fi
+
         sudo ip link set $OVS_PHYSICAL_BRIDGE up
         sudo ip link set br-int up
         sudo ip link set $PUBLIC_INTERFACE up