WebApp:`az webapp create --runtime` not idempotent

[Strepto]

Describe the bug

Command Name
az webapp create

Errors:

Parameter with name WEBSITE_NODE_DEFAULT_VERSION already exists.

To Reproduce:

Steps to reproduce the behavior. Note that argument values have been redacted, as they may contain sensitive information.

• az webapp create --name {} --resource-group {} --plan {} --runtime "node|12-lts"
• az webapp create --name {} --resource-group {} --plan {} --runtime "node|12-lts"

Expected Behavior

Running the same command twice should produce same result.

Environment Summary

Windows-10-10.0.19041-SP0
Python 3.6.8
Installer: MSI

azure-cli 2.13.0 *

Extensions:
application-insights 0.1.11

Additional Context

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc AzureAppServiceCLI (@AzureAppServiceCLI), antcp.

[yonzhan]

webapp

[panchagnula]

calvin (@calvinsID) seems like the test test_webapp_up_change_runtime_version is also failing due to the same reason - can you take a look?