Explicit merge conflicts for specific path

.gitattributes

DBBuild.php merge=merge-and-verify

.gitconfig

[merge "merge-and-verify"]
        name = Merge and verify file
        driver = ./bin/git-merge-and-verify %A %O %B

git-merge-and-verify

#!/bin/bash
git merge-file "${1}" "${2}" "${3}"
exit 1