Updating a git mirror of an SVN repository

I created a git mirror of an SVN repository by doing:

• Create a new repo on github
• mkdir mirror && cd mirror
• git svn init [svn url]
• git svn fetch -rHEAD
• git remote add origin [github url]
• git svn rebase
• git push origin master

This works great, and I can update it with simply:

• git svn rebase
• git push origin master

However, if I move to a different computer and want to update it, I tried:

• git clone [github url]
• git svn init [svn url]
• git svn fetch -rHEAD
• git remote add origin [github url]
• git svn rebase

but here I get:

"Unable to determine upstream SVN information from working tree history"

Can anyone explain the correct way to do this?