Code coverage in Phobos

[Walter Bright via Digitalmars-d]

On 7/28/2016 7:16 AM, Seb wrote:
> 4) CodeCov has a bunch of other features, for example browser extensions that
> integrate the code coverage report directly onto Github diffs:
>
> https://github.com/codecov/browser-extension

I installed the browser extension for Chrome, but it says "no coverage" for 
every Phobos PR I tried it on. Also, the umbrella icon is greyed out. 
Something's amiss?