Changed to short_month and re-ran tests.

lib/jekyll/post.rb

@@ -169,7 +169,7 @@ module Jekyll
           "i_day"      => date.strftime("%d").to_i.to_s,
           "i_month"    => date.strftime("%m").to_i.to_s,
           "categories" => categories.map { |c| URI.escape(c.to_s) }.join('/'),
-          "abrv_month" => date.strftime("%b"),
+          "short_month" => date.strftime("%b"),
           "output_ext" => self.output_ext
         }.inject(template) { |result, token|
           result.gsub(/:#{Regexp.escape token.first}/, token.last)

test/test_post.rb

@@ -227,7 +227,7 @@ class TestPost < Test::Unit::TestCase
 
         context "with custom abbreviated month date permalink" do
           setup do
-            @post.site.permalink_style = '/:categories/:year/:abrv_month/:day/:title/'
+            @post.site.permalink_style = '/:categories/:year/:short_month/:day/:title/'
             @post.process(@fake_file)
           end