Have a different approach on how to check if the modules file has changed.
Because the $FreeBSD$ keyword isn't expanded in the new version, we can't
just do a diff, check the return value and ignore the output.
Every new modules file, changed or not with regarding to the contents,
has at least four lines in the diff output (line number, old line,
seperator, new line). Only commit it if there are more than four
lines difference between it.