Enotra pregunta se recomienda usar.gitattributes para mantener el archivo rastreado pero no fusionado en una rama diferente, pero mi caso de uso a continuación parece no funcionar ...

mkdir git
cd git
git init
echo "B" > b.txt
git add b.txt 
git commit -m 'Initial commit'

echo "b.txt merge=keepMine" > .gitattributes
git add .gitattributes 
git config merge.keepMine.name "always keep mine during merge"
git config merge.keepMine.driver "keepMine.sh %O %A %B"
git commit -m 'Ignore b.txt'

git checkout -b test # Create a branch
git checkout master # Back to master and make change
echo "Only in master" > b.txt
git commit -a -m 'In master'

git checkout test
git merge master # The change in b.txt is being merged...

¿Alguna idea? Gracias..