From fe0e7dfb2d86f00ba3d072b066b328cd2fca4a4a Mon Sep 17 00:00:00 2001
From: Ben Balter <ben.balter@github.com>
Date: Tue, 5 Sep 2017 13:07:54 -0400
Subject: [PATCH] monkey patch https://github.com/jekyll/jekyll/pull/6338
 backport

---
 lib/jekyll-github-metadata/metadata_drop.rb | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/jekyll-github-metadata/metadata_drop.rb b/lib/jekyll-github-metadata/metadata_drop.rb
index af5f6bd..c228b1e 100644
--- a/lib/jekyll-github-metadata/metadata_drop.rb
+++ b/lib/jekyll-github-metadata/metadata_drop.rb
@@ -10,6 +10,13 @@ class MetadataDrop < Jekyll::Drops::Drop
 
       # See https://github.com/jekyll/jekyll/pull/6338
       alias_method :invoke_drop, :[]
+      def key?(key)
+        if self.class.mutable?
+          @mutations.key?(key)
+        else
+          !key.nil? && (respond_to?(key) || fallback_data.key?(key))
+        end
+      end
 
       def to_s
         require "json"