After a much longer than expected break due to moving and the resulting lack of Internet, plus WordPress releasing a package with a non-free file, the Debian package for WordPress 4.9.1 has been uploaded!
While this was all going on, there were 4 security issues found in WordPress which resulted in the 4.9.1 release.
Finally I got the time to look into the jshint problem and Internet to actually download the upstream files and upload the Debian packages. So version 4.9.1-1 of the packages have now been uploaded and should be in the mirrors soon. I’ll start looking at the 4.9.1 patches to see what is relevant for Stretch and Jessie.