[fleitz]

Did you mean to say 'brew upgrade bash'?

[sophacles]

That doesn't change the version of bash pointed at by /bin/sh which is a hardlink to the OSX supplied bash. Even if you previously relinked /bin/sh to a homebrew bash, it won't change versions by upgrading the installed bash.

[bashinator]

I suppose if you're being brave, you can nuke the built-in bash and symlink it back to brew's copy.