Unable to load extension 'azure-devops' in devops pipeline

Error :
Az devops works locally on agent.
When we ran through pipeline with CLI task ( powershell script) on agent, it throws error as az: 'devops' is not in the 'az' command group.

Also i could see the warning 'unable to load extension azure-devops' while loading.

azure-cli: 2.1.0,
command-modules-nspkg: 2.0.3,
core: 2.1.0,
nspkg: 3.0.4,
telemetry: 1.0.4
Extensions: azure-devops 0.17.0
Python location 'C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\python.exe'
Extensions directory 'C:\Program Files\Common Files\AzureCliExtensionDirectory'
Python (Windows) 3.6.6 (v3.6.6:4cf1f54eb7, Jun 27 2018, 02:47:15) [MSC v.1900 32 bit (Intel)]

**Expected behavior**
AZ devops command should work with Agent through devops pipeline.

**Screenshots**
Added Screenshot which shows unable to load extension 'azure-devops'