Unusual space inserted in signature string for Basic Reference Test

[liamdennehy]

While implementing Reference Tests in http-signatures-php I noticed I could not generate the provided Authorization Header in the Basic Test under Reference Tests, as it has a space after a parameter delimiter: headers="(request-target) host date", signature="qdx+H7PHHDZgy4...

Is this intentional? A Signature generator would not generate this line, so fail this reference test, and the specification doesn't mention being tolerant of spaces in between parameter keys for verification. I have scanned the document and can't actually find anywhere it explicitly describes how to compose the header line and the use of delimiters to separate parameters.