Enable preseeding testrepository with a number of streams

Project-config change Ib0e815ca1966f5b5806fb257b91ac7a25d4db18d will
change how the subunit streams are stored on the images. This commit
updates the logic around loading the subunit streams to handle both
the new format and the current method.

Change-Id: I8b71a96a34bf54aa9d60f1ef2f94e77103f6b914

devstack-vm-gate.sh

@@ -520,14 +520,25 @@ if [[ "$DEVSTACK_GATE_EXERCISES" -eq "1" ]]; then
     sudo -H -u stack ./exercise.sh
 fi
 
+function load_subunit_stream {
+    local stream=$1;
+    pushd /opt/stack/new/tempest/
+    sudo testr load --force-init $stream
+    popd
+}
+
+
 if [[ "$DEVSTACK_GATE_TEMPEST" -eq "1" ]]; then
+    #TODO(mtreinish): This if block can be removed after all the nodepool images
+    # are built using with streams dir instead
     if [[ -f /opt/git/openstack/tempest/.testrepository/0 ]]; then
-        pushd /opt/stack/new/tempest/
-        if [[ ! -d /opt/stack/new/tempest/.testrepository ]]; then
-            sudo testr init
-        fi
-        sudo sh -c 'cat /opt/git/openstack/tempest/.testrepository/0 | subunit-1to2 | testr load'
-        popd
+        temp_stream=`mktemp`
+        subunit-1to2 /opt/git/openstack/tempest/.testrepository/0 > $temp_stream
+        load_subunit_stream $temp_stream
+    elif [[ -d /opt/git/openstack/tempest/preseed-streams ]]; then
+        for stream in /opt/git/openstack/tempest/preseed-streams/* ; do
+            load_subunit_stream $stream
+        done
     fi
 
     # under tempest isolation tempest will need to write .tox dir, log files