Bugfix: don't add a fake digest to our fake binary
Bugfix: don't add a fake digest to our fake binary

If it's a local path, 0install complains that the digest is invalid because it
contains "/" characters, and it doesn't seem necessary anyway.

gfxmonk/0compile,dabrahams/0compile,0install/0compile,0install/0compile,dabrahams/0compile,0install/0compile,timbertson/0compile,gfxmonk/0compile,timbertson/0compile