tower-cli host modify -n host1 --variables "ansible_python_interpreter=/usr/bin/python26" -v
*** DETAILS: Checking for an existing record. *********************************
GET http://localhost:8013/api/v2/hosts/
Params: {'name': u'host1'}

*** DETAILS: Writing the record. **********************************************
PATCH http://localhost:8013/api/v2/hosts/16/
Data: {'name': u'host1', 'variables': u'ansible_python_interpreter=/usr/bin/python26'}

Error: The Tower server claims it was sent a bad request.

PATCH http://localhost:8013/api/v2/hosts/16/
Params: None
Data: {"name": "host1", "variables": "ansible_python_interpreter=/usr/bin/python26"}

Response: {"variables":["Cannot parse as JSON (error: No JSON object could be decoded) or YAML (error: Input type `str` is not a dictionary)."]}