Rudder tools

In some cases, merge all does not work correctly, It may not be able to update and checkout branch correctly before merge.

Here is a small example:

https://gist.github.com/VinceMacBuche/46cf72cbb7b6096dc61f

main extract

 $ git merge branches/rudder/2.11
Merge made by the 'recursive' strategy.
ncf-api-virtualenv/debian/conffiles | 2 +-
ncf-api-virtualenv/debian/dirs | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
$ git push NRM branches/rudder/3.0
Counting objects: 15, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 370 bytes | 0 bytes/s, done.
Total 3 (delta 2), reused 0 (delta 0)
To git@github.com:Normation/rudder-packages.git
b228eae..512ff82 branches/rudder/3.0 -> branches/rudder/3.0
Checkouting branches/rudder/3.0
$ git checkout branches/rudder/3.0
Déjà sur 'branches/rudder/3.0'
Votre branche est à jour avec 'NRM/branches/rudder/3.0'.
Pulling on NRM/branches/rudder/3.0
$ git pull --ff-only
Already up-to-date.
Pulling on NRM/branches/rudder/3.0
$ git pull --ff-only
Already up-to-date.
Merging 3.0 into master
$ git merge branches/rudder/3.0
Already up-to-date.
$ git push NRM master
To git@github.com:Normation/rudder-packages.git
! [rejected] master -> master (non-fast-forward)
error: impossible de pousser des références vers 'git@github.com:Normati