Without this change, the canonization of a header like Name:\r\n\tValue
wrongly leaves a space after the colon, and causing the signature
to be rejected.
@manu0401 This was fixed on the develop branch over 5 years ago by commit a65442161a6e59de49b3db9091754174e363c392. It's unfortunate there hasn't been a release since then (other than betas).
Without this change, the canonization of a header like Name:\r\n\tValue wrongly leaves a space after the colon, and causing the signature to be rejected.