Don't use a function argument as a for loop variable. It worked (mostly) but
Pylint frowns on it (redefined-argument-from-local) and I think Pylint has a
point.
If the configuration file is not found, raise an exception mentioning the
search path rather than just its last element.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>