jenkinsfile: fix branch merging

Change-Id: Ib0bb0985a396a9284229c79acc113a25c79c97bd

Jenkinsfile

@@ -136,8 +136,14 @@ See https://wiki.savoirfairelinux.com/wiki/Jenkins.jami.net#Configuration_client
 
             steps {
                 sh """git checkout ${params.CHANNEL}
+                      git status
+                      git reset --hard origin/nightly
+                      git status
                       # Submodules are generally not managed by merging
-                      git merge -X theirs --no-commit FETCH_HEAD || git add `git diff --name-status --diff-filter=U | awk '{print \$2}'`
+                      git merge -X theirs --no-commit FETCH_HEAD || true
+                      git status
+                      git checkout FETCH_HEAD -- daemon lrc client-qt
+                      git status
                    """
             }
         }