As interesting and useful as the answer to How to setup a git driver to ignore a folder on merge was, it did not answer the original question which still has me stumped.
I don't actually use Git, but I think this would work for your case:
Use something like what's specified here: https://gist.github.com/564416
git checkout master
git merge --no-commit --no-ff development
git reset -- /path/to/folder # revert updates from path
git commit
Again, I don't use git, I am just deferring to how I think things work based on my experience with TryGit.