test-lfs: avoid a bashism when spawning the server For zsh, this &> call is read as "& >", this spin the process without redirection. As a result the server grab stdout, which does not get closed at the end of the test. As a result `run-tests.py` hang there forever, waiting for the the stream for be close. (which is probably as issue on its own). Differential Revision: https://phab.mercurial-scm.org/D10396