git-svn clone error

I'm attempting to git-svn clone a subversion repository that contains a space in the name of a branch. This is the result (after many many revisions):

r148627 = fafd5730f356dcb80f72c9b93f976d9707755a03
(refs/remotes/origsvn/2.0_PriorToStuff)
Found possible branch point:
http://svn/repos/Products/my.product/branches/2.0 =>
http://svn/repos/Products/my.product/branches/2.0%20my_branch_name,
145211
W: Refspec glob conflict (ref: refs/remotes/origsvn/trunk):
expected path: Products/my.product/branches/trunk
    real path: Products/my.product/trunk
Continuing ahead with Products/my.product/trunk
Found branch parent: (refs/remotes/origsvn/2.0 my_branch_name)
5117c44d2cb5ee97d53f93f9c324d6f95ee5fdb5
Following parent with do_switch
Successfully followed parent
r148644 = da01bf418f28e2383a0fbbd7a73a6df0b0b800f6
(refs/remotes/origsvn/2.0 my_branch_name)
Found possible branch point:
http://svn/repos/Products/my.product/branches/2.0%20my_branch_name =>
http://svn/repos/Products/my.product/branches/2.0_branchname, 148650
fatal: Not a valid object name refs/remotes/origsvn/2.0 my_branch_name
cat-file commit refs/remotes/origsvn/2.0 my_branch_name: command
returned error: 128

Indeed, if I do "git cat-file commit refs/remotes/origsvn/2.0 my_branch_name" I get the help for git cat-file. If I escape the name, i.e. "git cat-file commit refs/remotes/origsvn/2.0%20my_branch_name" I get what I assume is the correct information.

I'm using Git for Windows, version 2.7.0. If this is a Windows-specific issue, I'm happy to report it over there.

Thanks, Mark