[Pacemaker] Constraints with and without rules

[Ben Beuchler]

I apologize for the cross-post if that's not kosher.  It appears
linux-ha still gets considerably more traffic than the pacemaker list.

Are these functionally equivalent on a cluster with symmetric-cluster=false?

This is the technique in the DRBD w/ v2 cluster document in the wiki
(albeit with a score of INFINITY instead of 100):

<rsc_location id="drbd0-loc-1" rsc="drbd0">
  <rule score="100">
    <expression value="node0" attribute="#uname" operation="eq"/>
    <expression value="node1" attribute="#uname" operation="eq"/>
  </rule>
</rsc_location>

And these are the type that seem to be favored in Mr. Beekhof's
excellent "Configuration Explained" document:

<rsc_location id="drbd0-loc-1" rsc="drbd0" node="node0" score="100"/>
<rsc_location id="drbd0-loc-2" rsc="drbd0" node="node1" score="100"/>

It seems both approaches should result in the same thing.  Any
particular reason to prefer one over the other?

FWIW, I'm running hb and pacemaker both from tip.

Thanks!

-Ben