Description of problem:
I had 3 controllers and 1 ceph node. I tried to scale up to 3 ceph so I ran the command:

openstack overcloud deploy --ceph-storage-scale 3 --plan-uuid 22e3f973-7cf9-407c-a612-32ddd5cab433

The stack update failed and I saw that 2 controllers were deleted. Also the tuskar plan showed that the controllers counter went down to 1:

constraints=[{u'definition': {u'min': u'0'}, ...
default=None                                 
description=None                             
hidden=None                                  
label=None                                   
name=Controller-1::count                     
parameter_type=number                        
value=1                                      
                                             
constraints=[{u'definition': {u'min': u'0'}, ...
default=None                                 
description=None                             
hidden=None                                  
label=None                                   
name=Ceph-Storage-1::count                   
parameter_type=number                        
value=1                                      
                                             
constraints=[{u'definition': {u'min': u'0'}, ...
default=None                                 
description=None                             
hidden=None                                  
label=None                                   
name=Compute-1::count                        
parameter_type=number                        
value=1                                      
                                             
constraints=[{u'definition': {u'min': u'0'}, ...
default=None                                 
description=None                             
hidden=None                                  
label=None                                   
name=Swift-Storage-1::count                  
parameter_type=number                        
value=0                                      
                                             
constraints=[{u'definition': {u'min': u'0'}, ...
default=None                                 
description=None                             
hidden=None                                  
label=None                                   
name=Cinder-Storage-1::count                 
parameter_type=number                        
value=0                                       


Version-Release number of selected component (if applicable):
python-rdomanager-oscplugin-0.0.8-13.el7ost.noarch


How reproducible:
100%


Steps to Reproduce:
1. Deploy with 3 controllers and 1 ceph
2. Try to scale up to 3 ceph by: "openstack overcloud deploy --ceph-storage-scale 3 --plan-uuid <...>"


Actual results:
Controller count went down to 1


Expected results:
Only the ceph count should have changed. Don't rely on the user to remember to always pass the same counters of all the other roles just to keep on to what is already deployed.