bug#8648: bug in date?

[Turner, Neil]

Maybe found a bug in date...  the following command:

$ date --date="yesterday 00:00 +1 day"
Mon May  9 16:59:00 PDT 2011

The date as I type this is May 10th... so I was expecting the output to be:
Tues May  10 00:00:00 PDT 2011

Thanks,

Neil