Git on SVN: space characters in branch names

Hi! I'm trying to move to Git on top of Subversion in my company
environment using Cygwin/Git 1.7.9. Therefore I'm trying to clone
a set of SVN repositories.

The SVN repository I'm trying to clone contains a commit, where a
branch was accidentally named "1.1.x _M1":

   git svn clone -s https://svnserver/repository project.git \
       --ignore-path=".*(?:1.1.x _M1|1.1.x%20_M1)"


This skips the initial commit, but still stumbles on the rename commit:

   Found possible branch point: \
	https://svnserver/repository/branches/1.1.x _M1 => \
	https://svnserver/repository/branches/1.1.x_M1, 2374
   fatal: Not a valid object name refs/remotes/1.1.x _M1
   cat-file commit refs/remotes/1.1.x _M1: command returned error: 128


Do I have to ignore the branch completely?

Thanks
- Ben