AWS API Gateway: Error when renaming path variable

This is a Bug Report

Description

Tried to rename a path variable and got the error.
Deployed a service with the following yml config:

service: aws-nodejs

provider:
    name: aws
    runtime: nodejs6.10

functions:
    hello:
        handler: handler.hello
        events:
            - http:
                path: /{pathvar}
                method: put

Then changed it to

service: aws-nodejs

provider:
    name: aws
    runtime: nodejs6.10

functions:
    hello:
        handler: handler.hello
        events:
            - http:
                path: /{pathVar} # Changed this variable
                method: put

Then tried to redeploy the service to update the variable name and got the error.

For bug reports:

• What went wrong?
  An error occurred while provisioning your stack: ApiGatewayResourcePathvarVar. A sibling ({pathvar}) of this resource already has a variable path part -- only one is allowed.
• What did you expect should have happened?
  Expected the service to deploy the new route over the old one. Renaming the path variable from pathvar to pathVar.
• What stacktrace or error message from your provider did you see? An error occurred while provisioning your stack: ApiGatewayResourcePathvarVar - A sibling ({pathvar}) of this resource already has a variable path part -- only one is allowed

Similar or dependent issues:

• #3075

Additional Data

• Serverless Framework Version you're using: 1.15.3
• Operating System: WIN 10
• Provider Error messages: An error occurred while provisioning your stack: ApiGatewayResourcePathvarVar. A sibling ({pathvar}) of this resource already has a variable path part -- only one is allowed.

If more information is needed, just let me know.

Reproduce the deployment using the shown service configuration, changing /{pathvar} to /{pathVar} and redeploying. Start by tracing the AWS API Gateway resource update path and the handling of renamed path variables; done means the route is updated without the sibling-variable error.