[BUG] PO links are broken

[Hannah-Doerpholz]

This relates to the issues #185 , #202 and #204 . None of the PO purls resolve correctly, I always get redirected to the "Term Not Found" page. When I navigate to PO through your home page it does show me the classes but when I click them I get redirected to the "Term Not Found" page.

[yongqunh]

It appears that the source to MS has issue: http://purl.obolibrary.org/obo/ms.owl
See an example that works fine: http://purl.obolibrary.org/obo/obi.owl.
however, the MS link appears to have issue.

[jamesaoverton]

Regarding MS: http://purl.obolibrary.org/obo/ms.owl works for me. I see an overview page for MS on Ontobee, listing metadata and top-level terms: https://ontobee.org/ontology/MS. However the pages for individual terms are not working: https://ontobee.org/ontology/MS?iri=http://purl.obolibrary.org/obo/MS_1000572. OLS is displaying MS and its terms, so I think the ms.owl file is fine.