[close #90] Use relative path for cache keys

lib/sprockets/base.rb

@@ -11,6 +11,7 @@
 require 'sprockets/resolve'
 require 'sprockets/server'
 require 'sprockets/source_map_utils'
+require 'sprockets/loader'
 
 module Sprockets
   # `Base` class for `Environment` and `Cached`.
@@ -49,9 +50,10 @@ def file_digest(path)
         # Caveat: Digests are cached by the path's current mtime. Its possible
         # for a files contents to have changed and its mtime to have been
         # negligently reset thus appearing as if the file hasn't changed on
-        # disk. Also, the mtime is only read to the nearest second. Its
+        # disk. Also, the mtime is only read to the nearest second. It's
         # also possible the file was updated more than once in a given second.
-        cache.fetch("file_digest:#{path}:#{stat.mtime.to_i}") do
+        key = UnloadedAsset.new(path, self).file_digest_key(stat.mtime.to_i)
+        cache.fetch(key) do
           self.stat_digest(path, stat)
         end
       end

lib/sprockets/dependencies.rb

@@ -51,13 +51,6 @@ def add_dependency(uri)
     end
     alias_method :depend_on, :add_dependency
 
-    # Internal: Resolve set of dependency URIs.
-    #
-    # Returns Array of resolved Objects.
-    def resolve_dependencies(uris)
-      uris.map { |uri| resolve_dependency(uri) }
-    end
-
     # Internal: Resolve dependency URIs.
     #
     # Returns resolved Object.