git-svn: wrong history after cloning a repository

Hi,

I'm currently struggeling with a strage behaviour of git-svn: After
git-svn-cloning a given repository (see attachment) in some cases the
git blame differs from the svn blame. The history looks like after a
merge all affected files have been added from scratch at this revision.

The behaviour can be observed using at least the following versions of
git:
1.7.10.2
1.8.1.4
1.8.2.GIT

Given: * svn-repository, svn-server 1.6.11, apache2 module via WEB DAV
       * repository like the one attached:
            * standard svn layout
            * branch ^/branches/feature1 copied from ^/trunk
            * changes made and files added on 
              project1/branches/feature1 by 'testuser1'
            * branch ^/branches/rc-1.0 copied from ^/trunk on 
              revX by 'mergeuser'
            * ^/branches/feature1 merged to ^/trunk on 
              revY by 'mergeuser'
            * ^/branches/rc-1.0 merged back to trunk revZ by 'mergeuser'

Action: git svn clone -s <repo-url>
        git blame <some_file_modified_on-feature1>

Observed behaviour: Changes being made on project1/branches/feature1
being associated to 'mergeuser' who integrated feature1 but not
implemented on that branch.

$ git blame src/file2.txt
9846ece6 (mergeuser 2013-04-11 14:31:21 +0000 1) content2-1
9846ece6 (mergeuser 2013-04-11 14:31:21 +0000 2) content2-2
9846ece6 (mergeuser 2013-04-11 14:31:21 +0000 3) content2-3

Action: svn blame <repo-url>/trunk/<some_file_modified_on-feature1>

Observed behaviour: Changes are correctly associated to user1

$ svn blame src/file2.txt
    4  testuser1 content2-1
    4  testuser1 content2-2
    4  testuser1 content2-3

I don't know yet which steps are really needed to re-create a repository
with this behaviour. My guess is that adding files together with a merge
(see r6 in the attached repository) has something to do with it.

Can you tell me whether this is a known issue or if there's a work
around for this? Unfortunately I'm not very into perl so I can't solve
this on my own. Please let me know if you need additional information.

Thanks

Frans