bug? in checkout with ambiguous refnames

Hello,

everything is clean:

	ukl@octopus:~/gsrc/linux-2.6$ git diff; git diff --cached

	ukl@octopus:~/gsrc/linux-2.6$ git checkout sgu/mxs-amba-uart
	warning: refname 'sgu/mxs-amba-uart' is ambiguous.
	Previous HEAD position was c13fb17... Merge commit '65e29a85a419f9a161ab0f09f9d69924e36d940e' into HEAD
	Switched to branch 'sgu/mxs-amba-uart'

OK, it might be a bad idea to have this ambiguity, still ...

	ukl@octopus:~/gsrc/linux-2.6$ git diff; git diff --cached --stat
	 arch/arm/mach-mxs/Kconfig                       |    2 ++
	 arch/arm/mach-mxs/clock-mx23.c                  |    2 +-
	 arch/arm/mach-mxs/clock-mx28.c                  |    2 +-
	 arch/arm/mach-mxs/devices-mx23.h                |    2 +-
	 arch/arm/mach-mxs/devices-mx28.h                |    2 +-
	 arch/arm/mach-mxs/devices.c                     |   17 ++---------------
	 arch/arm/mach-mxs/devices/Kconfig               |    1 -
	 arch/arm/mach-mxs/devices/amba-duart.c          |   15 +++++++--------
	 arch/arm/mach-mxs/include/mach/devices-common.h |    4 +---
	 9 files changed, 16 insertions(+), 31 deletions(-)
	ukl@octopus:~/gsrc/linux-2.6$ git diff refs/tags/sgu/mxs-amba-uart
	ukl@octopus:~/gsrc/linux-2.6$ git diff --cached refs/tags/sgu/mxs-amba-uart

So working copy and cache are at refs/tags/sgu/mxs-amba-uart, HEAD points to refs/heads/sgu/mxs-amba-uart

Best regards Uwe