Pacemaker: migrate resource without adding a "prefer" line in config

Using pacemaker in a 2 nodes master/slave configuration.

In order to perform some tests, we want to switch the master role from node1 to node2, and vice-versa. For instance if the current master is node1, doing

# crm resource migrate r0 node2

does indeed move the resource to node2. Then, ideally,

# crm resource migrate r0 node1

would migrate back to node1. The problem is that migrate added a line in the configuration to perform the switch

location cli-prefer-r0 r0 role=Started inf: node2

and in order to migrate back I have first to remove that line...

Is there a better way to switch master from one node to the other?