I have the following situation: I made some commits to my local repository, and then a huge merge of another branch (~150 commits) into the master - it had a lot of conflict
I've made a script to do this here. See the open issues for known limitations.
You'll need to first install rerere-train.sh onto your PATH. On Fedora this can be done with:
rerere-train.sh
install "$(rpm -ql git|grep '/rerere-train.sh$')" ~/bin