% tla make-archive --mirror email@example.com sftp://danga.com/home/martine/projects/a
Request for subsystem 'sftp' failed on channel 0
Error reading from server
My hacky fix is to edit src/tla/libarch/pfs-sftp.c and change the sftp command line from requesting the sftp subsystem (which for OpenSSH makes the command line include a -s and an sftp after the hostname) to requesting the sftp server directly: remove the -s and make the final argument /usr/lib/sftp-server.
It's a little annoying 'cause I have to rebuild tla every time I use it on a new computer, but it's not so bad as far compared to the slow-motion trainwreck that is most times I try to do something useful with these things.