`git-rev-parse master` not referred to by any ref?

Any idea how I got into this situation?:

	git$ git rev-parse master
	warning: refname 'master' is ambiguous.
	407c0c87e15b3cf60347f4fc0bcdb4d239de4163
	~/local/git$ git for-each-ref | grep master
	32ebe844c689d6e13e9875a0feefedca8dc1c6eb commit refs/heads/master
	e413074f1293e907d94af99330f0dd632a78b01f commit refs/remotes/linux-nfs/master
	0058a33a8eb5a8bfcfc5f5e769a2517cff4b73f1 commit refs/remotes/origin/master
	git$ git for-each-ref | grep 407c0
	git$ 

--b.