Removing labels on Github issues does not work with QtWebKit

Now that's a rather weird one...

When trying to remove a label from a Github issue using QtWebKit, the drop-down is updated but the label is not actually removed.

It works fine with Chromium and with a WebKitGTK+ based browser (dwb).

The attached video demonstrates the issue.

I contacted GitHub support as well, but (as expected, can't blame them), they said they only support the big browsers.