For some reason everytime I need to do this I forget the option. Maybe it is because the help for git checkout –help does not actually provide details for “-m” option.

git checkout -m <filename>

This restores the unresolved state, including all information about parent and merge base, which allows restarting the resolution.

There is of course the –theirs and –ours options available during a checkout if a merge is underway, but those options are explained in the help and the name of the option is self-explanatory, but -m does not stick in my head for some reason….