resources: Do not panic on autogrouped graph switches

Graph changes from autogrouped -> not autogrouped or vice versa cause a
panic (or I assume a leak) because we compared the auto grouped graph to
the ungrouped one, which would cause an Exit on an unstarted Vertex.
This includes a test that seems to reliably reproduces the issue.

test/shell/libmgmt-change2.sh

@@ -0,0 +1,10 @@
+#!/bin/bash -e
+
+go build -i -o libmgmt libmgmt-change2.go
+# this example should change graphs frequently, and then shutdown...
+$timeout --kill-after=30s 20s ./libmgmt &
+pid=$!
+wait $pid	# get exit status
+e=$?
+rm libmgmt	# cleanup build artefact
+exit $e