RUBY_RELEASE_MONTH   18 version.h      #if ONLY_ONE_DIGIT(RUBY_RELEASE_MONTH)
RUBY_RELEASE_MONTH   19 version.h      #define RUBY_RELEASE_MONTH_STR STRINGIZE(WITH_ZERO_PADDING(RUBY_RELEASE_MONTH))
RUBY_RELEASE_MONTH   21 version.h      #define RUBY_RELEASE_MONTH_STR STRINGIZE(RUBY_RELEASE_MONTH)