Scoped npm packages do not work with Nexus

I have set up a NPM proxy repository that proxies https://registry.npmjs.org

It seems that scoped packages e.g @sentry/browser are not working. All the non scoped packages are working.

For example:

My package.json has dependency 

"@sentry/browser": "4.4.1",

I have set up .yarnrc to connect my repository. When running for example 

yarn outdated --verbose

verbose 1.015 Request "https://my-repo/repository/npm-group/@sentry%2fbrowser" finished with status code 404.

verbose 1.028 Error: couldn't find @sentry/browser

    at NpmRegistry.<anonymous> (/usr/local/Cellar/yarn/1.15.2/libexec/lib/cli.js:31666:15)

    at Generator.next (<anonymous>)

    at step (/usr/local/Cellar/yarn/1.15.2/libexec/lib/cli.js:304:30)

    at /usr/local/Cellar/yarn/1.15.2/libexec/lib/cli.js:315:13

    at process._tickCallback (internal/process/next_tick.js:68:7)

error An unexpected error occurred: "couldn't find @sentry/browser".

info If you think this is a bug, please open a bug report with the information provided in "/Users/somepath/yarn-error.log".

info Visit https://yarnpkg.com/en/docs/cli/outdated for documentation about this command.

yarn is trying to fetch this request https://my-repo/repository/npm-group/@sentry%2fbrowser  where Nexus responds with 404. npm will make identical query and gets 404 also from the Nexus. Here the / in package name is URL encoded

It seems that Nexus expects the URL to be https://my-repo/repository/npm-group/@sentry/browser. At least this will not return 404. Here the / in the package name is NOT URL encoded.

Yarn outdated is just an example. It seems that there is same behavior whenever yarn actually tries to fetch the package data from the Nexus repository.

This happens at least with Nexus OSS 3.16.0-01and 3.15.2-01