When interpolating in strings passed to Formula#system, it should be
done in such a way that if any interpolated variables contain spaces,
they are either (a) passed as part of a list or (b) protected by quotes
if they are part of a long string (which is subject to shell expansion).
Otherwise, they will be split on the space when expanded by the shell
and passed as multiple arguments to whatever process is being executed.
Signed-off-by: Jack Nagel <jacknagel@gmail.com>
