GitLab

This program backups files and set of bare Git repositories into one Git repository.
Files are copied to blobs and then added to tree under certain place, and for
Git repositories, all reachable objects are pulled in with maintaining index
which remembers reference -> sha1 for every pulled repositories.

After objects from backuped Git repositories are pulled in, we create new
commit which references tree with changed backup index and files, and also has
all head objects from pulled-in repositories in its parents(*). This way backup
has history and all pulled objects become reachable from single head commit in
backup repository. In particular that means that the whole state of backup can
be described with only single sha1, and that backup repository itself could be
synchronized via standard git pull/push, be repacked, etc.

Restoration process is the opposite - from a particular backup state, files are
extracted at a proper place, and for Git repositories a pack with all objects
...