FIX: use tar -xzvf to extract maxmind vs Ruby wrappers

The tar/gz extractor in Ruby is somewhat buggy, instead rely on battle
tested `tar` and `gzip` Linux commands

lib/discourse_ip_info.rb

@@ -7,7 +7,7 @@ class DiscourseIpInfo
   include Singleton
 
   def initialize
-    open_db(File.join(Rails.root, 'vendor', 'data'))
+    open_db(DiscourseIpInfo.path)
   end
 
   def open_db(path)
@@ -16,38 +16,43 @@ class DiscourseIpInfo
     @cache = LruRedux::ThreadSafeCache.new(2000)
   end
 
+  def self.path
+    @path ||= File.join(Rails.root, 'vendor', 'data')
+  end
+
   def self.mmdb_path(name)
-    File.join(Rails.root, 'vendor', 'data', "#{name}.mmdb")
+    File.join(path, "#{name}.mmdb")
   end
 
   def self.mmdb_download(name)
     require 'rubygems/package'
     require 'zlib'
 
+    FileUtils.mkdir_p(path)
+
     uri = URI("https://geolite.maxmind.com/download/geoip/database/#{name}.tar.gz")
 
-    begin
-      tar_gz_file = Tempfile.new
-      tar_gz_file.binmode
-      tar_gz_file.write(Net::HTTP.get(uri))
-      tar_gz_file.close
+    tar_gz_file = Tempfile.new
+    tar_gz_file.binmode
+    tar_gz_file.write(Net::HTTP.get(uri))
+    tar_gz_file.close
 
-      begin
-        extractor = Gem::Package::TarReader.new(Zlib::GzipReader.open(tar_gz_file.path))
-        extractor.rewind
+    dest = File.join(Dir.tmpdir, "maxmind_#{SecureRandom.hex}")
+    FileUtils.mkdir_p(dest)
 
-        extractor.each do |entry|
-          next unless entry.full_name.ends_with?(".mmdb")
-          File.open(mmdb_path(name), "wb") { |f| f.write(entry.read) }
-        end
-      ensure
-        extractor.close
+    Discourse::Utils.execute_command('tar', '-xzvf', tar_gz_file.path, "-C", dest)
+
+    Dir.glob("#{dest}/**/*.mmdb").each do |path|
+      if path.include?(name)
+        FileUtils.mv(path, mmdb_path(name))
+      else
+        Rails.logger.warn("Skipping unknown mmdb file during ip database update #{path}")
       end
-
-    ensure
-      tar_gz_file.close
-      tar_gz_file.unlink
     end
+
+  ensure
+    FileUtils.rm_rf(dest) if dest
+    FileUtils.rm(tar_gz_file) if tar_gz_file
   end
 
   def mmdb_load(filepath)