In the origin visit calendar, duplicate visit dates link to https://archive.softwareheritage.org/browse/origin/directory/?visit_id=`<visit_id>` (which returns a 400 error)

1. Go to https://archive.softwareheritage.org/browse/origin/visits/?origin_url=deb://Debian/packages/tempest*
2. Select 2017
3. Click on one of the yellow dates (eg. 27 November 2017, 17:40:49 UTC)
4. This links to https://archive.softwareheritage.org/browse/origin/directory/?visit_id=30