daemon should report error when trying to set environment variables, and there are two variables with the same name

[gregsadetsky]

the payload below - with the test variable appearing twice - was accepted by the daemon when POST'ing to https://(server)/api/projects/(project)/env

the daemon only kept the "later" value (of new variable), but I believe that it should have returned an error instead

{
    "envVariables":
    [
        {
            "name": "another",
            "value": "test"
        },
        {
            "name": "test",
            "value": ""
        },
        {
            "name": "testt",
            "value": ""
        },
        {
            "name": "test",
            "value": "new variable"
        }
    ]
}