A---B---C branch-1 D---E---F branch-2
$ git checkout branch-2
$ git cherry-pick B
A---B---C branch-1 D---E---F---B' branch-2
A---B---C branch-1 D---E---F branch-2
$ git checkout branch-2
$ git cherry-pick B
A---B---C branch-1 D---E---F---B' branch-2