oldweb: work around annoying ERB deprecation in Ruby 2.6

Updated patch by: Takashi Kokubun at
  https://bugs.ruby-lang.org/issues/15478

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/oldweb.rb b/lib/oldweb.rb
index 910afaf..daa5cc5 100644
--- a/lib/oldweb.rb
+++ b/lib/oldweb.rb
@@ -269,7 +269,11 @@ class Oldweb
       erbout = "_erbout_#{file_var}"
     end
 
-    template = klass.new(template, nil, '<>', erbout)
+    if ERB.instance_method(:initialize).parameters.assoc(:key)
+      template = klass.new(template, trim_mode: '<>', eoutvar: erbout)
+    else
+      template = klass.new(template, nil, '<>', erbout)
+    end
     @template_cache[file] = template
   end