Example travis run from #1143: https://travis-ci.org/github/cloudflare/cfssl/jobs/742000951

Culprit could be asn1: structure error: tags don't match (6 vs {class:0 tag:16 length:1094 isCompound:true}). Could be because of this change: https://golang.org/doc/go1.15

asn1.Unmarshal: now rejects tags and Object Identifiers which are not minimally encoded according to X.690 DER.

https://github.com/cloudflare/cfssl/blob/master/helpers/helpers.go#L317 does return (asn1.SyntaxError) asn1: syntax error: integer is not minimally encoded