Author: Hiroshi Nakamura <email@example.com>
Date: Fri Feb 3 11:33:22 2012 +0900
JRUBY-6419: GzipReader encodings still not right; breaks "gem install"
Having scanned zlib.c of CRuby again, I found that GzReader#read()
(without size parameter) sets Encoding but GzReader#read(size) does
not. So make JRuby version do the same as CRuby.
It could be a bug of CRuby. (It should not set Encoding for read() as