I don't think this is an issue specific to lerna, I actually think it is nvm related (though I commented out nvm from my .bash_profile to test that, without success).
I'm trying to lerna bootstrap but it keeps using (and failing) an older version (1.3.2) of yarn than what I'm running:
$ yarn -v
1.22.4
$ lerna bootstrap
info cli using local version of lerna
lerna notice cli v3.22.1
lerna info versioning independent
lerna info bootstrap root only
yarn install v1.3.2
error An unexpected error occurred: "patterns.map is not a function".
info If you think this is a bug, please open a bug report with the information provided in "yarn-error.log".
info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command.
lerna ERR! yarn install --mutex network:42424 --non-interactive exited 1 in 'root'
lerna ERR! yarn install --mutex network:42424 --non-interactive exited 1 in 'root'
$ yarn -v
1.22.4
I rooted around in my filesystem and removed ~/.yarn and ~/node_modules/yarn and everything works now.