Merge only changes from branch B into current branch A

merge.sh

# After merging master into this branch, let's use the files from master and ignore our conflicts
git checkout --theirs some/file/in/my/repo/with/conflicts
# Now let's add those files into the commit
git add .
# This should result in something like this when running 'git status'
# On branch blah
# Your branch is up-to-date with 'origin/blah'.
# All conflicts fixed but you are still merging.
#   (use "git commit" to conclude merge)
# Changes to be committed:
#   ...
# Conclude the merge
git commit