fatal: ambiguous argument 'HEAD': unknown revision or path not in the working tree.

From: Thomas Glanzmann <thomas@glanzmann.de>
Date: Jun 8, 2007, 10:08 UTC
Message-ID: <20070608100831.GA2335@cip.informatik.uni-erlangen.de>

Hello,

        (s017241) [/usr/src/linux-2.6] git checkout v2.6.20
        warning: You appear to be on a branch yet to be born.
        warning: Forcing checkout of v2.6.20.
        fatal: ambiguous argument 'HEAD': unknown revision or path not in the working tree.
        Use '--' to separate paths from revisions
        Cannot detach HEAD

(s017241) [/usr/src/linux-2.6] git version git version 1.5.2.1

what is going wrong here?

        Thomas