We now offer completion support for git-bisect's subcommands,
as well as ref name completion on the good/bad/reset subcommands.
This should make interacting with git-bisect slightly easier on
the fingers.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <junkio@cox.net>