pgraph: Move the quiesce done indicator to avoid deadlock

This avoids a deadlock on resource failure when retry==0. Without this
we would never exit. This adds a test in too!

test/shell/exec-fail.sh

@@ -0,0 +1,9 @@
+#!/bin/bash -e
+
+# should take a few seconds plus converged timeout, and test we don't hang!
+# TODO: should we return a different exit code if the resources fail?
+# TODO: should we be converged if one of the resources has permanently failed?
+$timeout --kill-after=20s 15s ./mgmt run --yaml exec-fail.yaml --converged-timeout=5 --no-watch --no-pgp --tmp-prefix &
+pid=$!
+wait $pid	# get exit status
+exit $?