Bug in the HTTP interface: broken navigation at prefix level

[TobiasWeigel]

Hi,
this came up as a side note during the dev meeting in Februar as well, but I didn't pursue this further until now. There seems to be a broken HTML view.
If I access https://handle.dkrz.de/handles/ I do not get a list of the available prefixes (as of now, 2) but only links back to the same page, with each link titled 'handles'. See screenshot.
I vaguely remember that this was working at either Pieter's or Tibor's laptop or production installation, so it might be a config issue.