Modifying the History - Git Recipes - page 290

If you want to keep the history stored under the second parent of the merge commit
then use -m 2 parameter, such as:
$ git revert --no-edit -m 2 HEAD ∼
This command produces the snapshot consisting of revisions m1 , m2 , m3 , f1 , f2 ,
f3 , m6 . This case is illustrated in Figure 8-11 .
Figure 8-11 . The snapshot obtained with $ git revert --no-edit -m 2 HEAD ∼
If you forget to indicate the branch you want to keep, git will refuse to revert the
merge commit. The command will fail producing following message:
error: Commit XXXXXX is a merge but no -m option was
given.
fatal: revert failed
8-10. Cherry-picking revisions