Merge branch 'tr/protect-low-3-fds'

When "git" is spawned in such a way that any of the low 3 file descriptors is closed, our first open() may yield file descriptor 2, and writing error message to it would screw things up in a big way. * tr/protect-low-3-fds: git: ensure 0/1/2 are open in main() daemon/shell: refactor redirection of 0/1/2 from /dev/null