If I run the CLI installer the first question it asks is about language. Immediately before the list of available languages is the following PHP warning.

PHP Warning: str_repeat(): Second argument has to be greater than or equal to 0 in /home/andrew/Desktop/code/moodle/dev/master/admin/cli/install.php on line 249

Warning: str_repeat(): Second argument has to be greater than or equal to 0 in /home/andrew/Desktop/code/moodle/dev/master/admin/cli/install.php on line 249