[[!comment format=mdwn
 username="joey"
 subject="""comment 1"""
 date="2015-04-06T21:15:46Z"
 content="""
This has nothing to do with git-annex-shell or anything server-side. We can
see this in the error messages; the error comes from client-side git-annex
and not from git-annex-shell at all.

For annex.sshcaching to work, git-annex has to set GIT_SSH=git-annex, and
then git calls it with the name of the hostname to ssh to.

So, your client-side git-annex is new enough to do sshcaching on sync, but
then when git runs $GIT_SSH, the git-annex program it then runs seems
to be an older version of git-annex. Which does not appreciate being called
as if it is ssh.

Fix this version confusion and your problem will be solved. Maybe
have an older version of git-annex somewhere in PATH where git finds it.
Or, maybe you have a ~/.config/git-annex/program file that points to some
older installation of git-annex.

(It might also help to upgrade to a current version, ideally before filing
a bug report; it's quite possible some change has been made that will
make whatever your setup is work.)
"""]]