Gramae mirror has only the upstream branch. Currently the branch i'm interested by is 1.4_fixes. Using git svn is a mess with the branches, and it's so damn slow.
Use the wiki instructions but replace trunk with the fixes branch. Should work and it is not too slow. You don't need the whole history, use param " --revision 45000:HEAD" or something.
I do "git svn rebase" often and the recent changes come very quickly. Same with commits by "git svn dcommit".
You guys should seriously think to use GitHub or a similar git service (you can even run your own...) you probably loose a lot of possible contributions, it's so easy with GH PR system !
"loose a lot of possible contributions" ... right. Please let's not go into this nonsense again. The Git <-> SVN arguments lasted literally years in this forum and the same FUD was repeated.
It turned out that Git was usable all the time, either with Graeme's mirror or with git-svn link. Now it is documented and Git formatted patches accepted but there was no rush of contributors using Git.
Now we are lucky to have some new contributors but they all seem to use SVN. Typically if somebody truly wants to contribute, he will use the tools available. After all most of the complexity comes from actually modifying the code, revision control tool is a minor challenge compared to that.