I haven't taken a look at the spec, but assuming what's noted in that issue comment is indeed the case, then I find it surprising that something as obvious as this would not be fixed/raised during the RFC and review of the spec itself.
There was/is no RFC for the ZIP file format (there is for gzip and the DEFLATE algorithm). It was Phil Katz releasing a text file called APPNOTE.TXT describing the file structure (latest version is available at https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT ).
It almost makes .zip feel much more proprietary than it is!