Reparando “perl: warning: Setting locale failed.” en Ubuntu Server

Un error que me he encontrado en varias ocasiones en instalaciones de Ubuntu Server es el siguiente: perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = “en_US.UTF-8″ are supported and installed on your system. perl: warning: Falling back to the standard locale (“C”). [...]