Heredoc with powerline

When I try to use heredoc with powerline, I get blank segments before each new line: How can I fix it so that it looks lsomething ike this:

Just create a theme for continuation (file ~/.config/powerline/themes/shell/continuation.json) with the following content:

{
    "segments": {
        "left": [
            {
                "type": "string",
                "contents": ">",
                "highlight_groups": ["continuation"]
            }
        ]
    }
}

Here's the result: