Fix broken Fuseki when using a context path in the URL

[kinow]

Version

main e9c3c30

What happened?

We fixed this in #2392 a few days ago, but apparently something broke that again (see same issue linked).

#2392 (comment) reported by OP @peutch

• fix it again
• write a test to avoid future regressions

Relevant output and stacktrace

Quoting the comment linked above.

>    using the main branch is breaking again something (http://localhost:3030/fuseki does not serve index.html and forcing http://localhost:3030/fuseki/index.html goes wrong).
>    using e1e9bf4 and just cherry picking 2f3a293 is working as expected.
>    Probably one commit in between breaks something. One of the dep updates in 3a09ec5? Didn't tried to bisect.

Are you interested in making a pull request?

Maybe