Description of problem:
After deploying OpenShift 4.2.9 into Azure we have a constant stream of UpdateError warnings on the master machines:
~~~~
17s         Warning   FailedUpdate   machine/master-0                  UpdateError: failed to update machine "master-0": found attempt to change immutable state
4m45s       Warning   FailedUpdate   machine/master-1                  UpdateError: failed to update machine "master-1": found attempt to change immutable state
2m19s       Warning   FailedUpdate   machine/master-2                  UpdateError: failed to update machine "master-2": found attempt to change immutable state
~~~~

Theser errors appear since the initial installation, nothing have changed on the machineconfig objects since running the installer.

Errors in machine-controller:
~~~~
I1205 14:54:04.370797       1 controller.go:133] Reconciling Machine "master-2"
I1205 14:54:04.370869       1 controller.go:304] Machine "master-2" in namespace "openshift-machine-api" doesn't specify "cluster.k8s.io/cluster-name" label, assuming nil cluster
I1205 14:54:04.370885       1 actuator.go:196] Checking if machine master-2 exists
I1205 14:54:04.577767       1 reconciler.go:360] Found vm for machine master-2
I1205 14:54:04.577797       1 reconciler.go:380] Machine XXXXXXXX-60c0-4ff0-XXXX-fd6209978249 is running
I1205 14:54:04.577806       1 controller.go:244] Reconciling machine "master-2" triggers idempotent update
I1205 14:54:04.577814       1 actuator.go:161] Updating machine master-2
I1205 14:54:04.815151       1 machine_scope.go:179] master-2: status unchanged
E1205 14:54:04.831998       1 actuator.go:83] Machine error: failed to update machine "master-2": found attempt to change immutable state
E1205 14:54:04.832020       1 controller.go:246] Error updating machine "openshift-machine-api/master-2": requeue in: 20s
I1205 14:54:04.832036       1 controller.go:337] Actuator returned requeue-after error: requeue in: 20s
~~~~

These errors are filling the event stream with red warning events. 

Version-Release number of selected component (if applicable):
4.2.9


How reproducible:
Have not been able to reproduce this in-house


Steps to Reproduce:
1.n/a
2.
3.

Actual results: Machine events are spammed with the messages 'UpdateError: failed to update machine "master-2": found attempt to change immutable state' for master machines.


Expected results: These events are either not fed to the machine events or are suppressed. (If these events are 'normal' for master machines)


Additional info: