Can i suggest that you expire and remove the downloads directory from meta-swi-extras as follows
￼￼￼￼￼￼￼￼git filter-branch --index-filter 'git rm -r --cached --ignore-unmatch downloads' --prune-empty -f -- --all
git reflog expire --expire=now --all
git gc --aggressive --prune=now
This reduces the repository to < 100M
It appears at some stage there were downloads pushed into this repository that can/should be removed.
I would also suggest supplying the git repositories for the kernel at least and spliting the source into seperate files.
there is no need to include the kernel/poky/meta-openembedded into the source tarball.
git clone git://git.yoctoproject.org/poky -b dizzy yocto2/poky/
git clone git://git.openembedded.org/meta-openembedded -b dizzy yocto2/meta-openembedded