https://tools.wmflabs.org/gerrit-patch-uploader/: https://s3.amazonaws.com/github/ribbons/forkme_left_darkblue_121621.png

Loading from external providers are discouraged. Please see parent tasks and J65.
In your case possible solutions would be:

• Use https://simonwhitaker.github.io/github-fork-ribbon-css/, we provide the css on https://tools-static.wmflabs.org/cdnjs/ajax/libs/github-fork-ribbon-css/
• https://tools.wmflabs.org/static-browser/ may have provided this image, but the service may be down at the moment
• Host the image file in your tool