The installer has hard-coded references to the 172.22.0.0/24 subnet, with only partial support for modifying the IPs associated with this.
These networks should be fully configurable including whether to turn of DHCP in the cluster or not.
https://github.com/openshift/installer/pull/2931/files upstream has information about how to change the provisioning network.
For QE to verify this bug, I would set provisioningNetworkCIDR in the install-confg to some other value than the default (e.g. 172.23.0.0/16), and verify hosts use IP's in that network to be provisioned.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.