ZDoom's source code is hosted on a Git repository since the release of ZDoom 2.7.0. Previously, it was hosted on a Subversion repository.
What is Git, and why?
Git is a distributed version control system. All the reasons for using the old Subversion repository also apply to Git, but in addition Git is distributed. The advantages over a centralized system like SVN include enhanced protection against data loss (SVN depends on the centralized server being online), simpler branching and forking, better automatic merging, among others. When the decision was taken to move away from Subversion, both Git and Mercurial (Hg) were considered, with the final decision being to use Git.
DRD Team hosts development builds of ZDoom, GZDoom, and other Doom-related programs such as Doom Builder 2 and SLADE 3. They are sometimes still called "SVN builds" out of habit and to keep things simple, despite offering a mix of SVN builds (DB2), Git builds (ZDoom, GZDoom), and Hg builds (ECWolf, Doomseeker).