From a79597d8b3fef6379e4c291036c6ccb7210b31fe Mon Sep 17 00:00:00 2001
From: Zach Schneider <schneidmaster@gmail.com>
Date: Thu, 2 Jan 2014 23:45:39 -0500
Subject: [PATCH] Modified github.js to ensure __ isn't escaped at beginning of
 line

    fixes #1791
---
 core/shared/vendor/showdown/extensions/github.js |  2 +-
 core/test/unit/client_showdown_int_spec.js       | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/core/shared/vendor/showdown/extensions/github.js b/core/shared/vendor/showdown/extensions/github.js
index f7138e5a90..d11e2c04dd 100644
--- a/core/shared/vendor/showdown/extensions/github.js
+++ b/core/shared/vendor/showdown/extensions/github.js
@@ -43,7 +43,7 @@
 
 
                     //prevent foo_bar and foo_bar_baz from ending up with an italic word in the middle
-                    text = text.replace(/(^(?! {4}|\t)\w+_\w+_\w[\w_]*)/gm, function (x) {
+                    text = text.replace(/(^(?! {4}|\t)(?!__)\w+_\w+_\w[\w_]*)/gm, function (x) {
                         return x.replace(/_/gm, '\\_');
                     });
 
diff --git a/core/test/unit/client_showdown_int_spec.js b/core/test/unit/client_showdown_int_spec.js
index 67c3e1cdeb..ebaf1ba5ce 100644
--- a/core/test/unit/client_showdown_int_spec.js
+++ b/core/test/unit/client_showdown_int_spec.js
@@ -60,6 +60,18 @@ describe("Showdown client side converter", function () {
         });
     });
 
+    it("should not escape double underscores at the beginning of a line", function () {
+        var testPhrases = [
+                {input: "\n__test__\n", output: /^<p><strong>test<\/strong><\/p>$/}
+            ],
+            processedMarkup;
+
+        testPhrases.forEach(function (testPhrase) {
+            processedMarkup = converter.makeHtml(testPhrase.input);
+            processedMarkup.should.match(testPhrase.output);
+        });
+    });
+
     it("should not treat pre blocks with pre-text differently", function () {
         var testPhrases = [
                 {input: "<pre>\nthis is `a\\_test` and this\\_too and finally_this_is\n</pre>", output: /^<pre>\nthis is `a\\_test` and this\\_too and finally_this_is\n<\/pre>$/},