Description of problem: When running the scaleup playbook, we are receiving the error message below in the node logs:

~~~
Apr 21 22:42:30 host.example.com atomic-openshift-node[26981]: W0421 22:42:30.733206   26981 subnets.go:112] Could not find an allocated subnet for node: host.example.com, Waiting...
~~~

It would appear we are hitting something similar to the KCS's linked below:

https://access.redhat.com/solutions/2092731
https://access.redhat.com/solutions/3392491

However, we are not setting the values for osm_cluster_network_cidr or osm_host_subnet_length to the default values should be used:

~~~
osm_cluster_network_cidr="10.128.0.0/14"
osm_host_subnet_length=9

Per: https://access.redhat.com/solutions/3392491 the max should be ~512 nodes
~~~

We know that there is a supported limit of 300 nodes per cluster in 3.2.

        3.2: https://docs.openshift.com/enterprise/3.2/install_config/install/prerequisites.html#host-recommendations

And it appears we are below that limit:

# oc get nodes | wc -l
266


Version-Release number of selected component (if applicable):
3.2.1.31-1

How reproducible:
Able to reproduce this on the environment using the scaleup playbook. 


Steps to Reproduce:
1.Run the scaleup playbook to add an additional host. 
2.
3.

Actual results:
Scaleup fails

Expected results:
Add additional node to the cluster. 

Additional info: