not possible to install with yarn due to dependency in git repo

Yarn refuses to install this package as it has a git repo as a dependency due to it not having a hash. Can it be removed and turned into a reference to the npm repository, or it still necessary to keep it?

This is the dep: git://github.com/mjohnston/scroller

And this is the error log from yarn add react-canvas:

yarn add v0.27.5
warning ../../package.json: No license field
warning ../../../../../package.json: No license field
[1/4] Resolving packages...
error Refusing to download the git repo {"hostname":"github.com","protocol":"git:","repository":"git://github.com/mjohnston/scroller.git"} over plain git without a commit hash
info Visit https://yarnpkg.com/en/docs/cli/add for documentation about this command.

This is caused by a long-standing issue in yarn: https://github.com/yarnpkg/yarn/issues/2117, and a quick fix might be to specify the commit hash to use.