Fixes multiple config loading. Closes #973. Rel: #945.

bin/jekyll

@@ -46,7 +46,7 @@ command :build do |c|
   c.syntax = 'jekyll build [options]'
   c.description = 'Build your site'
 
-  c.option '--config [CONFIG_FILE]', Array, 'Custom configuration file'
+  c.option '--config CONFIG_FILE[,CONFIG_FILE2,...]', Array, 'Custom configuration file'
   c.option '--future', 'Publishes posts with a future date'
   c.option '--limit_posts MAX_POSTS', 'Limits the number of posts to parse and publish'
   c.option '-w', '--watch', 'Watch for changes and rebuild'
@@ -54,7 +54,6 @@ command :build do |c|
   c.option '--drafts', 'Render posts in the _drafts folder'
 
   c.action do |args, options|
-    options.defaults :serving => false
     options = normalize_options(options.__hash__)
     options = Jekyll.configuration(options)
     Jekyll::Commands::Build.process(options)
@@ -65,7 +64,7 @@ command :serve do |c|
   c.syntax = 'jekyll serve [options]'
   c.description = 'Serve your site locally'
 
-  c.option '--config [CONFIG_FILE]', Array,'Custom configuration file'
+  c.option '--config CONFIG_FILE[,CONFIG_FILE2,...]', Array, 'Custom configuration file'
   c.option '--future', 'Publishes posts with a future date'
   c.option '--limit_posts MAX_POSTS', 'Limits the number of posts to parse and publish'
   c.option '-w', '--watch', 'Watch for changes and rebuild'

lib/jekyll/configuration.rb

@@ -106,7 +106,7 @@ module Jekyll
     #
     # Returns this configuration, overridden by the values in the file
     def read_config_file(file)
-      configuration = dup
+      configuration = clone
       next_config = YAML.safe_load_file(file)
       raise "Configuration file: (INVALID) #{file}".yellow if !next_config.is_a?(Hash)
       Jekyll::Logger.info "Configuration file:", file
@@ -120,7 +120,7 @@ module Jekyll
     # Returns the full configuration, with the defaults overridden by the values in the
     # configuration files
     def read_config_files(files)
-      configuration = dup
+      configuration = clone
 
       begin
         files.each do |config_file|
@@ -143,7 +143,7 @@ module Jekyll
     #
     # Returns the backwards-compatible configuration
     def backwards_compatibilize
-      config = dup
+      config = clone
       # Provide backwards-compatibility
       if config.has_key? 'auto'
         Jekyll::Logger.warn "Deprecation:", "'auto' has been changed to " +