Missing "http" in DRONE_RPC_SERVER leads to an error

I am using the following command to run the agent on the same machine as the server:

docker run

as long as “http” is missed in DRONE_RPC_SERVER, I was receiving an error as follow:

2019/07/10 11:33:56 [ERR] POST ci.test.com://localhost:8080/rpc/v1/request request failed: Post ci_test_com://localhost:8080/rpc/v1/request: unsupported protocol scheme “ci_test_com”.

However, running the server with missing “http” in DRONE_SERVER_HOST works successfully.

Do I need to use “http” or it is a bug?

For a list of configuration parameters and sample values see https://docs.drone.io/administration/agents/linux-amd64/