diff -Nru rubygems-integration-1.15/debian/changelog rubygems-integration-1.15.1/debian/changelog
--- rubygems-integration-1.15/debian/changelog	2020-01-05 22:45:05.000000000 +0000
+++ rubygems-integration-1.15.1/debian/changelog	2021-01-02 17:59:20.000000000 +0000
@@ -1,3 +1,10 @@
+rubygems-integration (1:1.15.1-1bbox1~xenial1) xenial; urgency=medium
+
+  * Better support for Ruby 2.7, backported from 1.16 and 1.17
+  * Bump epoch to override Focal's version, which kills older ruby support
+
+ -- John Leach <john@brightbox.co.uk>  Sat, 02 Jan 2021 17:59:20 +0000
+
 rubygems-integration (1.15-1bbox3~xenial1) xenial; urgency=medium
 
   * Build for Ubuntu
diff -Nru rubygems-integration-1.15/lib/rubygems/defaults/operating_system.rb rubygems-integration-1.15.1/lib/rubygems/defaults/operating_system.rb
--- rubygems-integration-1.15/lib/rubygems/defaults/operating_system.rb	2020-01-03 16:59:33.000000000 +0000
+++ rubygems-integration-1.15.1/lib/rubygems/defaults/operating_system.rb	2021-01-02 17:51:08.000000000 +0000
@@ -28,6 +28,9 @@
       ].compact
     end
 
+    # This was not defined in ruby2.5, and is now defined again in ruby2.7;
+    # therefore the alias call must be conditional
+    alias :upstream_default_specifications_dir :default_specifications_dir if RUBY_VERSION >= '2.7'
     def default_specifications_dir
       File.join(Gem.upstream_default_dir, 'specifications', 'default')
     end
@@ -44,7 +47,13 @@
 
   if RUBY_VERSION >= '2.7'
     class Gem::Specification
-      def rubyforge_project=(x)
+      begin
+        alias :upstream_rubyforge_project= :rubyforge_project=
+        def rubyforge_project=(x)
+        end
+      rescue NameError
+        # rubyforge_project= was removed in RubyGems 3.1.4
+        # If method rubyforge_project= is not present, that's ok
       end
     end
   end