master: gamedir command broken

Where foo is a valid gamedir (exists at ~/.xonotic/foo and contains a non-zero size file, ~/.xonotic/foo/bar),
Adding the following to autoexec.cfg results in a segfault: gamedir foo data
Adding the following to autoexec.cfg does not crash, but also does not add the gamedir: gamedir "foo data"

NB: if specified on cmdline OR via the command, the last gamedir MUST be data for xonotic to save files in the correct location.