If you are migrating from an older version of redis that is outside your vagrant box then run this first so when your new DB is up it has the same info:
# Unloading should create a dump.rdb file in /usr/local/var/dump.rdb
launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.redis28.plist
# Then uninstall redis28
brew uninstall redis28
Then: