Content negotiation requesting UNIXREF failing silently with some SICI DOIs

[gbilder]

See, for example:

curl -LH "Accept:application/vnd.crossref.unixref+xml" https://doi.org/10.1175%2F1520-0477%281996%29077%3C0935%3AWOTWSM%3E2.0.CO%3B2

10.1175/1520-0477(1996)077<0935:WOTWSM>2.0.CO;2