title: "InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)" when updating package list
body: <p>Here is what I see in my terminal:</p>
  
  <pre><code>user@user-OptiPlex-9020:~$ sudo apt-get update
  Ign http://extras.ubuntu.com trusty InRelease                                  
  Ign http://in.archive.ubuntu.com trusty InRelease                              
  Get:1 http://dl.google.com stable InRelease                                    
  100% [1 InRelease gpgv 1,661 B] [Connecting to 192.168.0.90 (192.168.0.90)] [WaSplitting up /var/lib/apt/lists/partial/dl.google.com_linux_chrome_deb_dists_stable_InRelease intoIgn http://dl.google.com stable InRelease                                      
  E: GPG error: http://dl.google.com stable InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)
  </code></pre>
  
  <p>I have the required authentication information in /etc/apt/apt.conf file:</p>
  
  <pre><code>Acquire::http::proxy "http://username:password@192.168.0.90:8080/";
  Acquire::https::proxy "https://username:password@192.168.0.90:8080/";
  Acquire::ftp::proxy "ftp://username:password@192.168.20.0:8080/";
  </code></pre>
  
  <p>I am not able to figure out the problem.</p>