tool/merger.rb: Fetch a diff in the patch format

It expects "Subject:", so it needs to be a patch file.

1 files changed, 1 insertions, 1 deletions

diff --git a/tool/merger.rb b/tool/merger.rb
index 934a265094..795e97a86e 100755
--- a/tool/merger.rb
+++ b/tool/merger.rb
@@ -263,7 +263,7 @@ else
     end
 
     # Merge revision from Git patch
-    git_uri = "https://github.com/ruby/ruby/commit/#{git_rev}.diff"
+    git_uri = "https://github.com/ruby/ruby/commit/#{git_rev}.patch"
     resp = Net::HTTP.get_response(URI(git_uri))
     if resp.code != '200'
       abort "'#{git_uri}' returned status '#{resp.code}':\n#{resp.body}"