in 2.7 ruby RUBY_REVISION is a hash of a commit

Author: viuginick1

lib/debase/ruby_core_source.rb

@@ -50,7 +50,7 @@ def self.create_makefile_with_core(hdrs, name)
     def self.deduce_packaged_source_dir(ruby_dir)
       prefix = File.dirname(__FILE__) + '/ruby_core_source/'
       expected_directory = prefix + ruby_dir
-      if RUBY_REVISION > 0 and File.directory?(expected_directory)
+      if (RUBY_REVISION.is_a? String or RUBY_REVISION > 0) and File.directory?(expected_directory)
         expected_directory
       else
         # Fallback to an older version.