Invalid dates in git log

Hi there,

I'm experiencing a date issue with certain commits in Git in Linus's 2.6 kernel repository.

One commit has a date from 2019, while another commit has a date from
1970. Although Git has been around for a while and seeing a Linux
commit from 2019 would be cool, I think there's something wrong here.

My questions are:

1) Is this a problem in the Git software?
2) Or is it a data corruption issue in the repository?
3) Can it be fixed and should I contact anyone to get it fixed?

I'm doing some log analysis and these two dates mess up my charts.

Steps to reproduce:

$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git

$ git  log  a27ac38efd6dc6dccebfc9bcc475ab4aa5fc4a56 -1
commit a27ac38efd6dc6dccebfc9bcc475ab4aa5fc4a56
Author: Len Brown <len.brown@intel.com>
Date:   Fri Apr 5 00:07:45 2019 -0500

    [ACPI] fix merge error that broke CONFIG_ACPI_DEBUG=y build

    Signed-off-by: Len Brown <len.brown@intel.com>

$ git  log  224426f168aa4af3dcb628e6edaa824d32d60e6f  -1
commit 224426f168aa4af3dcb628e6edaa824d32d60e6f
Author: Ursula Braun <braunu@de.ibm.com>
Date:   Thu Jan 1 01:00:01 1970 +0100

    qeth: remove header_ops bug

    Remove qeth bug caused by commit:
    [NET]: Move hardware header operations out of netdevice.

    Signed-off-by: Ursula Braun <braunu@de.ibm.com>
    Signed-off-by: Jeff Garzik <jeff@garzik.org>

Thanks,

Eirik.