Backport Request: kernel-yocto: fix checkout bare-cloned kernel repositories

Please help to bring this patch to Jethro branch:

http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=4487e3a4205188cf53930147c7e88d98f0d8a8e0

This fix was from updating kernel labs for Jethro and we think it should be a good one on Jethro.

Thanks lot!

As this is against OE-Core, this should really reference the git.openembedded.org cgit, not Poky.

Please update the reference.

Sau!