Older versions of git store the absolute path of the submodules'
repository as stored in the super-project, e.g.:
$ cat some-submodule/.git
gitdir: /path/to/super-project/.git/modules/some-submodule
Obviously, this is not very reproducible.
More recent versions of git, however, store relative paths, which
de-facto makes it reproducible.
Fix older versions by replacing the absolute paths with relative ones.
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
8fe9894f65