You can clone with
HTTPS or Subversion.
There are still a few references to SVN in the code. Especially the development environment is recognized by the .svn folder in PIWIK_ROOT.
A simple $ grep -R .svn . shows some more references.
In d48af43: Properly recognize the development environment.
In 235405e: .svn dir does not exist anymore.
In 47b9122: svn export won't work anymore. Instead we do a git clone -b $VERSION
There is still a reference to trunk/ for nightly builds, not sure
how that is supposed to work.
In a0e81a4: Proper checkout of tag by version. Previous one was for branches..
In 073af4e: Remove .svn references. refs #3736
In 39768c4: refs #3736