Since Git 2.9 (April 2016), you can try:
git pull --allow-unrelated-histories origin master
But check why those branches are no longer common though.
Maybe there was a force push rewriting all the history of origin/master.
In which case, if you don’t have local commits of your own, it is best to reset your branch to the new one:
Warning: this will delete any untracked file, and reset your repository to origin/master
(You can try it in a copy of your current local clone)
git fetch
# Warning: RESET AHEAD
git reset --hard origin/master