[ruby/rubygems] Consume remaining gzip data in open_tar_gz to suppress zlib warning

When a GzipReader is closed before all compressed data is consumed,
zlib emits "attempt to close unfinished zstream; reset forced" warning.
This happens in open_tar_gz because the TarReader stops reading at the
end-of-archive marker, leaving unconsumed compressed data in the stream.

ruby/rubygems@2b047e11fc

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 2 people

lib/rubygems/package.rb

@@ -556,6 +556,15 @@ def open_tar_gz(io) # :nodoc:
       tar = Gem::Package::TarReader.new gzio
 
       yield tar
+    ensure
+      # Consume remaining gzip data to prevent the
+      # "attempt to close unfinished zstream; reset forced" warning
+      # when the GzipReader is closed with unconsumed compressed data.
+      begin
+        gzio.read
+      rescue Zlib::GzipFile::Error, IOError
+        nil
+      end
     end
   end