Implementation for local fetcher

Signed-off-by: Clinton Wolfe <clintoncwolfe@gmail.com>

lib/inspec/dependencies/resolver.rb

@@ -62,7 +62,7 @@ module Inspec
           begin
             dep.resolved_source
           rescue Inspec::FetcherFailure
-            Inspec::Log.debug("Failed to fetch #{dep.name}, a falling back to archives if possible")
+            Inspec::Log.debug("Failed to fetch #{dep.name}, falling back to archives if possible")
             retry if fallback_to_archive_on_fetch_failure(dep)
           end
         end

lib/inspec/fetcher/local.rb

@@ -100,6 +100,19 @@ module Inspec::Fetcher
       end
     end
 
+    def update_from_opts(opts)
+      changed = false
+
+      old_val = @archive_shasum
+      new_val = opts[:sha256]
+      unless old_val == new_val
+        @archive_shasum = new_val
+        changed = true
+      end
+
+      changed
+    end
+
     def perform_shasum(target)
       return @archive_shasum if @archive_shasum
       raise(Inspec::FetcherFailure, "Profile dependency local path '#{target}' does not exist") unless File.exist?(target)