Use of uninitialized value $u in substitution (s///) at /usr/share/perl5/Git/SVN.pm line 106.

I am running git-svn to convert a large repository on Sourceforge. I often get this error:

Use of uninitialized value $u in substitution (s///) at /usr/share/perl5/Git/SVN.pm line 106.
Use of uninitialized value $u in concatenation (.) or string at /usr/share/perl5/Git/SVN.pm line 106.

Workaround is editing .git/config and deleting all lines with branches and tags in the [svn-remote] section, but I have to do this very often.

The error occurs while using the svn2git wrapper (https://github.com/nirvdrum/svn2git) and also while using git svn directly. The error is reported more than once on the svn2git issue tracker on github, on different lines, but I did not find any reference of anyone reporting this upstream to get it fixed, so that is why I am filing this bug.
This is the issue at line 106: https://github.com/nirvdrum/svn2git/issues/99 - first seen 2 years ago. The relevant part of the code hasn't changed since then.

$ lsb_release -rd
Description: Ubuntu 14.10
Release: 14.10

$ apt-cache policy git-svn
git-svn:
  Installed: 1:2.1.3-1
  Candidate: 1:2.1.3-1
  Version table:
 *** 1:2.1.3-1 0
        500 http://be.archive.ubuntu.com/ubuntu/ vivid/universe amd64 Packages
        100 /var/lib/dpkg/status
     1:2.1.0-1 0
        990 http://be.archive.ubuntu.com/ubuntu/ utopic/universe amd64 Packages
     1:1.9.1-1 0
        500 http://be.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages
     1:1.8.3.2-1 0
        500 http://be.archive.ubuntu.com/ubuntu/ saucy/universe amd64 Packages

What I expect to happen: git-svn initalizes value $u before it gets used.

I searched for "Use of uninitialized value $u in substitution (s///) at /usr/share/perl5/Git/SVN.pm line 106." on Launchpad and Askubuntu, but did not find any previous reports of this issue.