To revert a merge commit, you need to use: git revert -m <parent number>. So for example, to revert the recent most merge commit using the parent with number 1 you would use:
git revert -m 1 HEAD
To revert a merge commit before the last commit, you would do:
git revert -m 1 HEAD^
Use git show <merge commit SHA1> to see the parents, the numbering is the order they appear e.g. Merge: e4c54b3 4725ad2
git merge documentation: http://schacon.github.com/git/git-merge.html
git merge discussion (confusing but very detailed): http://schacon.github.com/git/howto/revert-a-faulty-merge.txt
If you don't want to commit, or want to commit later (commit message will still be prepared for you, which you can also edit):
git revert -n <commit>
git reset --hard HEAD^
Use the above command to revert merge changes.
If I understand you correctly, you're talking about doing a
svn merge -rn:n-1
to back out of an earlier commit, in which case, you're probably looking for
git revert
Source: Stackoverflow.com