Please not that sometimes this will not work:
git checkout --ours path/to/file
or
git checkout --theirs path/to/file
I did this instead, assuming HEAD is ours and MERGE_HEAD is theirs
git checkout HEAD -- path/to/file
or:
git checkout MERGE_HEAD -- path/to/file
After we do this and we are good:
git add .
If you want to understand more, see wonderful post of torek here : git checkout --ours does not remove files from unmerged files list