[xehndgkq] Git over sneakernet

Initial clone from Parent to Child: git bundle create mybundle master (as documented in git-bundle manpage).

"git pull" by Child from Parent: well documented in git-bundle manpage.

Move changes from Child to Parent: (on Child) git format-patch origin/master -o patchdir, transfer files in patchdir to Parent, (on Parent) git am patchdir/*

More conservatively, (on Parent) git checkout -b temp-branch, git am on temp-branch, merge temp-branch back on to master.

It can also be done both directions with git bundle: https://git-scm.com/book/en/v2/Git-Tools-Bundling