glib-2.34.3, opposed to 2.32.4, starts to depend on docbook. Hopefully, this dependency can be removed and docbook does not have to be installed.
This is only a build-time dependency. So don't worry, if you are e.g. building gentoo packages for an embedded device, docbook-xml-dtd-4.1.2-r6 will be pulled in only on your build machine (which certainly has more than enough disk space), and not on the target device where you are installing packages (where flash space might be limited).
It's still annoying. More dependencies are always worse - I actually don't care for building for a device with minimal disk-space, I don't want to pollute a system with sufficient disk space with undesired packages, either.
If we were to argue by the old, pretty worn-out, "disk space is cheap" argument, why would anyone give a damn if glib pulled in KDE and Haskell? Disk space is cheap, after all, isn't it...