touch avn-file1.txt
git add avn-file1.txt
git commit -m "avn-file1.txt"
...
touch avn-file3.txt
git add avn-file3.txt
git commit -m "avn-file3.txt"

pick fdf9508 avn-file1.txt
pick 0633d9c avn-file2.txt
pick 4d71f77 avn-file3.txt

pick fdf9508 avn-file1.txt
pick 0633d9c avn-file2.txt
pick 4d71f77 avn-file3.txt

touch fcs-file1.txt
git add fcs-file1.txt
git commit -m "fcs-file1.txt"
...
touch fcs-file3.txt
git add fcs-file3.txt
git commit -m "fcs-file3.txt"

pick fdf9508 avn-file1.txt
pick 0633d9c avn-file2.txt
pick 4d71f77 avn-file3.txt
pick 7dd4772 fcs-file1.txt
pick f33cdda fcs-file2.txt
pick c54c562 fcs-file3.txt

git remote add fcs <адрес репозитория подрядчика>

[vasya@wrkst1 avn]$ git pull fcs master
remote: Counting objects: 7, done.
remote: Compressing objects: 100% (6/6), done.
remote: Total 6 (delta 2), reused 0 (delta 0)
Unpacking objects: 100% (6/6), done.
From gitserver:polygon/fcs
 * branch            master     -> FETCH_HEAD
Updating 4d71f77..c54c562
Fast-forward
 fcs-file1.txt | 0
 fcs-file2.txt | 0
 fcs-file3.txt | 0
 3 files changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 fcs-file1.txt
 create mode 100644 fcs-file2.txt
 create mode 100644 fcs-file3.txt

touch avn-megafix1.txt
git add avn-megafix1.txt
git commit -m "avn-megafix1.txt"

git remote add avn <адрес репозитория подрядчика>

git pull avn master