git clone svn: authors from authors file are ignored, authors-prog works, but crashes on branch points

Hi, i am observing some weired "git svn clone" behavior during my try to migrate the Scaffold Hunter [1] SVN repository [2] to Git:

if i just use the command 

$ git svn clone svn://svn.code.sf.net/p/scaffoldhunter/code --no-metadata -s code

everything went smoothly. Now i wanted to replace the authors SVN-logins by useful names and created a mapping file with the following content: 

anjenson = Andrew Zhilka <> bernhard.dick = Bernhard Dick <> dominic.sacre = Dominic Sacré <> doxmoxbox = doxmoxbox <> falkn = Falk Nette <> henning.garus = Henning Garus <> kakl = Karsten Klein <> klein = Karsten Klein <> lappie00 = Jeroen Lappenschaar <> michael.hesse = Michael Hesse <> nlskrg = Nils Kriege <nlskrg@gmail.com> philipp.kopp = Philipp Kopp <> philipp.lewe = Philipp Lewe <> schrins = Sven Schrinner <> shamshadnpti = Shamshad Alam <> srenner7 = Steffen Renner <> sturm89 = Werner Sturm <> thomas.schmitz = Thomas Schmitz <> thorsten.fluegel = Thorsten Flügel <> till.schaefer = Till Schäfer <till2.schaefer@tu-dortmund.de> tillschaefer = Till Schäfer <till2.schaefer@tu-dortmund.de>

I executed:

$ git svn clone svn://svn.code.sf.net/p/scaffoldhunter/code --authors-file=/home/till/temp/code-authors-transform.txt --no-metadata -s code

and got the error message "Author: klein not defined in /home/till/temp/code-authors-transform.txt file". I tried a workaround by using a python script to return the entries i have already defined in the authors file:

$ git svn clone svn://svn.code.sf.net/p/scaffoldhunter/code --authors-file=/home/till/temp/code-authors-transform.txt --authors-prog=/home/till/temp/authors.py --no-metadata -s code

The import process now went over the "klein" commit. The weired thing is, that a few SVN usernames seem to be recognized in the authors file and a few are passed to my script (I logged the output). However, at the first revision, where a tag was added in the SVN repo the cloning process crashed with the error message: 

Found possible branch point: svn://svn.code.sf.net/p/scaffoldhunter/code/trunk => svn://svn.code.sf.net/p/scaffoldhunter/code/branches/subsearch, 17 Use of uninitialized value $u in substitution (s///) at /usr/lib64/perl5/vendor_perl/5.20.2/Git/SVN.pm line 101. Use of uninitialized value $u in concatenation (.) or string at /usr/lib64/perl5/vendor_perl/5.20.2/Git/SVN.pm line 101. refs/remotes/origin/trunk: 'svn://svn.code.sf.net/p/scaffoldhunter/code' not found in ''

One problem I am seeing in the SVN repo is, that between the revisions 97 and 102 the trunk folder was absent. the old one was moved to some subfolder and a new one was created. Therefore, I started the cloning beginning with rev 102 using the command line option "-r102:HEAD". However, the same error occurred for some later tag (the first tag after rev 102). 

Found possible branch point: svn://svn.code.sf.net/p/scaffoldhunter/code/trunk => svn://svn.code.sf.net/p/scaffoldhunter/code/tags/release-2.0, 1565 Use of uninitialized value $u in substitution (s///) at /usr/lib64/perl5/vendor_perl/5.20.2/Git/SVN.pm line 101. Use of uninitialized value $u in concatenation (.) or string at /usr/lib64/perl5/vendor_perl/5.20.2/Git/SVN.pm line 101. refs/remotes/origin/trunk: 'svn://svn.code.sf.net/p/scaffoldhunter/code' not found in ''

I would be very glad if someone has a hint about what is going wrong here. Is this a bug in git or is something wrong with the SVN repo?

used software versions: 
- git 2.5.0 
- subversion 1.8.14

Regards, Till

[1] http://scaffoldhunter.sourceforge.net/ [2] https://svn.code.sf.net/p/scaffoldhunter/code/trunk