rosdep update: "No address associated with hostname"

edit

I have a Intel RealSense robotic development kit. I installed Ubuntu 16.04.

$ which rosdep
/usr/bin/rosdep
$ rosdep --version
0.11.5
$ apt-cache policy python-rosdep
python-rosdep:
  Installed: 0.11.5-1
  Candidate: 0.11.5-1
  Version table:
 *** 0.11.5-1 500
        500 http://packages.ros.org/ros/ubuntu xenial/main amd64 Packages
        500 http://packages.ros.org/ros/ubuntu xenial/main i386 Packages
        100 /var/lib/dpkg/status
     0.11.4-2 500
        500 http://us.archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
        500 http://us.archive.ubuntu.com/ubuntu xenial/universe i386 Packages

so version is not the problem. I'm able to ping raw.githubusercontent.com and get results

$ ping raw.githubusercontent.comPING raw.githubusercontent.com (151.101.48.133) 56(84) bytes of data.
64 bytes from raw.githubusercontent.com (151.101.48.133): icmp_seq=1 ttl=56 time=74.5 ms
64 bytes from raw.githubusercontent.com (151.101.48.133): icmp_seq=2 ttl=56 time=80.8 ms
64 bytes from raw.githubusercontent.com (151.101.48.133): icmp_seq=3 ttl=56 time=24.8 ms
64 bytes from raw.githubusercontent.com (151.101.48.133): icmp_seq=4 ttl=56 time=21.9 ms
^C
--- raw.githubusercontent.com ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3004ms
rtt min/avg/max/mdev = 21.915/50.552/80.889/27.279 ms

However, when I get to installing rosdep, I get this:

$ sudo apt -y install ros-kinetic-desktop-full python-rosinstall ros-kinetic-realsense-camera
[sudo] password for <>: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
python-rosinstall is already the newest version (0.7.8-1).
ros-kinetic-desktop-full is already the newest version (1.3.0-0xenial-20161211-213832-0800).
ros-kinetic-realsense-camera is already the newest version (1.6.1-0xenial-20161204-170602-0800).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
$ sudo rosdep init
Wrote /etc/ros/rosdep/sources.list.d/20-default.list
Recommended: please run

    rosdep update
$ rosdep update
reading in sources list data from /etc/ros/rosdep/sources.list.d
ERROR: unable to process source [https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/osx-homebrew.yaml]:
    <urlopen error [Errno -5] No address associated with hostname> (https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/osx-homebrew.yaml)
ERROR: unable to process source [https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/base.yaml]:
    <urlopen error [Errno -5] No address associated with hostname> (https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/base.yaml)
ERROR: unable to process source [https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/python.yaml]:
    <urlopen error [Errno -5] No address associated with hostname> (https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/python.yaml)
ERROR: unable to process source [https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/ruby.yaml]:
    <urlopen error [Errno -5] No address associated with hostname> (https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/ruby.yaml)
ERROR: unable to process source [https://raw.githubusercontent.com/ros/rosdistro/master/releases/fuerte.yaml]:
    Failed to download target platform data for gbpdistro:
    <urlopen error [Errno -5] No address associated with hostname>
Query rosdistro ...