git svn rebase - could not detach HEAD (howto fix)

Sounds gross but that is the curt message:

$ git svn rebase

First, rewinding head to replay your work on top of it…
could not detach HEAD
rebase refs/remotes/trunk: command returned error: 1


Not very helpful, no clue, can't even buy a vowel. But if you try something else, the error message begin to make the problem more obvious:

$ git co refs/remotes/trunk
error: Untracked working tree file 'public/images/plugout_button.gif' would be overwritten by merge.


Well… then git-svn should've said so!

$ rm public/images/plugout_button.gif
$ git svn rebase
First, rewinding head to replay your work on top of it…
Applying ….


So there. This post is so that I commit it to my long term memory, aka Google.