EDIT: Workaround. Now we understand the issue, here is the solution: do
git svn fetch -r REVISION:HEAD
where REVISION is t
In case of using Git for Windows, make sure to upgrade from 2.20.1 to either previous (2.20.0), next (2.21.0) or any other. Mentioned version has a bug making "git svn fetch" hang, which was later fixed.