Jean-Noël Avila [off-list ref] writes:
For a short time, I had the same issue. We came up using "git bundle"
to bundle changes and exchange them via email.
The setup was to work in two separate branches. The roaming developper
started a new branch when leaving. After some work, she sent the
commits on her branch as a bundle file. The origin merged the branch
extracted from the developper's bundle and sent back the bundle of the
changes on origin since the last merge.
No doubt that both side need to understand well the workflow of
fetch/merge. Bundle files can be encrypted for better security.
Yes, the above describes exactly what "bundle" was invented for.