My git config looked like that
[svn-remote "svn"]
url = https://svn.example.com/svn/project
fetch = trunk:refs/remotes/trunk
branches = branches/*:refs/remotes/*
tags = tags/*:refs/remotes/tags/*
(created with git svn init -s https://svn.example.com/svn/project
)
Then added the tags and branches dir with svn (can't do that with git-svn).
after that, I was able to create tags with
git svn tag XXX
Then I tried what you wanted to, created a tag in SVN directly:
svn copy -r 17 https://svn.example.com/svn/project/trunk https://svn.example.com/svn/project/tags/lastStable
Went back to git and executed
git svn fetch
and got
Found possible branch point: https://svn.example.com/svn/project/trunk => https://svn.example.com/svn/project/tags/lastStable, 17
Found branch parent: (refs/remotes/tags/lastStable) e8fb9785b9c23d4039dd7516931974f4ecc725ec
Following parent with do_switch
Successfully followed parent
r21 = e84f0194791f3555623280b0384f2c5531e4c579 (refs/remotes/tags/lastStable)
soo...I don't know exactly where your problem is.
The new remotes/tags/lastStable works fine for me now ;)
I used svn 1.6.16 and git 1.7.6