For some reason, tree spawn isn't working on my cluster after reboot - so turn it off so MTT doesn't bomb

This commit was SVN r28296.

contrib/platform/greenplum/bend/linux.conf

@@ -60,6 +60,7 @@
 
 #default hostfile
 orte_default_hostfile = /home/common/hosts
+plm_rsh_no_tree_spawn = 1
 #ras_slurm_enable_dyn_alloc = 1
 #ras_slurm_config_file = /home/common/slurm/conf/slurm.conf