In git 1.7.9.5 I could run the following lines without error:
export SVNPASS=readonly git clone git@github.com:dtenenbaum/RGalaxy.test.git cd RGalaxy.test/ g
there are many proposed fixes for this issue:
https://github.com/nirvdrum/svn2git/issues/132 https://github.com/nirvdrum/svn2git/pull/145
in my opinion this is a bug in svn2git