In the latest release, the PDF version has the appropriate links to different sections of the text. For example on p.11, at the end of section 1.8, it has:
“Fortunately, Git has several methods of handling conflicts. Knowing how these work is an important part of mastering Git. We’ll cover all of the tools you can use in Section 5.4, Handling Conflicts, on page 61.”
In the epub version, “Section 5.4, Handling Conflicts, on page 61” shows up as “(as yet) unwritten content.”) This happens consistently throughout the epub book. This is very unfortunate and annoying.