cannot extract the gz file that is downloaded - ruby

Question

the gz file is downloaded but is not extractable. Here is a working program that downloads the file but itself cannot extract it.
require 'open-uri'
require 'zlib'
(2017..2017).each{|year|
(1..1).each{|weekno|
symbols.each{|instrument|
url="https://tickdata.fxcorporate.com/#{instrument}/#{year}/#{weekno}.csv.gz"
puts url
begin
open("#{instrument}#{year}#{weekno}.csv.gz", 'w') do |local_file|
open(url) do |remote_file|
local_file.write(Zlib::GzipReader.new(remote_file).read)
end
end
Zlib::GzipReader.open("#{instrument}#{year}#{weekno}.csv.gz") {|gz|
print gz.read
}
rescue StandardError => e
puts e.message
puts e.backtrace.inspect
end
}
}
}
I get error
https://tickdata.fxcorporate.com/AUDCAD/2017/1.csv.gz
not in gzip format
["downloadtickfiles.rb:26:in `initialize'", "downloadtickfiles.rb:26:in `open'", "downloadtickfiles.rb:26:in `block (3 levels) in <main>'", "downloadtickfiles.rb:16:in `each'", "downloadtickfiles.rb:16:in `block (2 levels) in <main>'", "downloadtickfiles.rb:15:in `each'", "downloadtickfiles.rb:15:in `block in <main>'", "downloadtickfiles.rb:14:in `each'", "downloadtickfiles.rb:14:in `<main>'"]