Description of problem:
Impossible to turn RHEVH host to global maintenance via CLI, in HE environment, which blocks the RHEVM upgrade for engine that's running on top of RHEVH host.  

[root@alma03 ~]# hosted-engine --set-maintenance --mode=global
Traceback (most recent call last):
  File "/usr/lib64/python2.6/runpy.py", line 122, in _run_module_as_main
  File "/usr/lib64/python2.6/runpy.py", line 34, in _run_code
  File "/usr/lib/python2.6/site-packages/ovirt_hosted_engine_setup/set_maintenance.py", line 72, in <module>
  File "/usr/lib/python2.6/site-packages/ovirt_hosted_engine_setup/set_maintenance.py", line 56, in set_mode
  File "/usr/lib/python2.6/site-packages/ovirt_hosted_engine_ha/client/client.py", line 255, in set_maintenance_mode
  File "/usr/lib/python2.6/site-packages/ovirt_hosted_engine_ha/env/config.py", line 101, in set
IOError: [Errno 30] Read-only file system: '/var/lib/ovirt-hosted-engine-ha/ha.conf'

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


How reproducible:
100%

Steps to Reproduce:
1.Deploy HE on RHEVH and try to put the host in to the global maintenance mode.
2.
3.

Actual results:
IOError: [Errno 30] Read-only file system: '/var/lib/ovirt-hosted-engine-ha/ha.conf'

Expected results:
Global and local maintenance have to be available for RHEVH.

Additional info:
You might consider moving required config files to TMP for maintenance to be possible.