switch UNICODE_BETA to NO (one more try, first try didn't work)

Unicode version 12.1.0 was officially released on May 7th, 2019.
    There were no changes at all from the "real" beta
    published shortly after the new era name "Reiwa" was announced.
    So we can switch UNICODE_BETA back to NO.

    common.mk: switch UNICODE_BETA back to NO
    tool/downloader.rb: add additional conditions to avoid an error
                        when moving from beta to final

common.mk

@@ -19,7 +19,7 @@ enable_shared = $(ENABLE_SHARED:no=)
 
 UNICODE_VERSION = 12.1.0
 UNICODE_EMOJI_VERSION = 12.0
-UNICODE_BETA = YES
+UNICODE_BETA = NO
 
 ### set the following environment variable or uncomment the line if
 ### the Unicode data files should be updated completely on every update ('make up',...).

tool/downloader.rb

@@ -94,7 +94,7 @@ class Downloader
         super(UNICODE_PUBLIC+name_dir_part+beta_name, name, dir, since, options)
       else
         index_file = Pathname.new(under(dir, name_dir_part+'index.html'))
-        if index_file.exist?
+        if index_file.exist? and name_dir_part !~ /^(12.1.0|emoji\/12.0)/
           raise "Although Unicode is not in beta, file #{index_file} exists. " +
                 "Remove all files in this directory and in .downloaded-cache/ " +
                 "because they may be leftovers from the beta period."