Add deprecation support for pages in subfolders with relative permalinks.

lib/jekyll/configuration.rb

@@ -19,7 +19,10 @@ module Jekyll
       'limit_posts'   => 0,
       'lsi'           => false,
       'future'        => true,           # remove and make true just default
-      'pygments'      => true,           # remove and make true just default
+      'pygments'      => true,
+
+      'relative_permalinks' => true,     # backwards-compatibility with < 1.0
+                                         # will be set to false once 1.1 hits
 
       'markdown'      => 'maruku',
       'permalink'     => 'date',

lib/jekyll/page.rb

@@ -144,5 +144,9 @@ module Jekyll
     def index?
       basename == 'index'
     end
+
+    def uses_relative_permalinks
+      permalink && !permalink.include?(File.expand_path(@dir, site.source))
+    end
   end
 end

lib/jekyll/site.rb

@@ -231,6 +231,7 @@ module Jekyll
       end
 
       self.pages.each do |page|
+        relative_permalinks_deprecation_method if page.uses_relative_permalinks
         page.render(self.layouts, payload)
       end
 
@@ -418,5 +419,15 @@ module Jekyll
       post.categories.each { |c| self.categories[c] << post }
       post.tags.each { |c| self.tags[c] << post }
     end
+
+    def relative_permalinks_deprecation_method
+      if config['relative_permalinks'] && !@deprecated_relative_permalinks
+        Jekyll::Logger.warn "Deprecation:", "Starting in 1.1, permalinks for pages" +
+                                            " in subfolders must be absolute" +
+                                            " permalinks relative to the site" +
+                                            " source."
+        @deprecated_relative_permalinks = true
+      end
+    end
   end
 end