For computers that aren't in the en_US locale, a vaguely annoying message appears when one vagrant sshes:
$ vagrant ssh Last login: Sun May 24 16:18:57 2015 from 10.0.2.2 -bash: warning: setlocale: LC_ALL: cannot change locale (en_GB.UTF-8)
It would be nice if, during the initial provision, we detected and installed the host's locale (e.g. sudo locale-gen de_DE.UTF-8) and got rid of that warning.
I guess one could just force the locale to be en_US, but that's the boring solution.