[Fix] ensure if `npm link` fails, that `$IFS` is not improperly set.
[Fix] ensure if `npm link` fails, that `$IFS` is not improperly set.

https://github.com/creationix/nvm/issues/1519#issuecomment-297850323
PeterDaveHelloKitchen/nvm,PeterDaveHello/nvm,creationix/nvm,evocateur/nvm,edwmurph/nvm,edwmurph/nvm,ljharb/nvm,PeterDaveHelloKitchen/nvm,ljharb/nvm,evocateur/nvm,PeterDaveHello/nvm,creationix/nvm