Ubuntu18.04安装melodic时，rosdep update时失败

现象：
jiang@ubuntu:~$ rosdep update
reading in sources list data from /etc/ros/rosdep/sources.list.d
Hit https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/osx-homebrew.yaml
Hit https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/base.yaml
Hit https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/python.yaml
Hit https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/ruby.yaml
Hit https://raw.githubusercontent.com/ros/rosdistro/master/releases/fuerte.yaml
Query rosdistro index https://raw.githubusercontent.com/ros/rosdistro/master/index-v4.yaml
Skip end-of-life distro “ardent”
Skip end-of-life distro “bouncy”
Skip end-of-life distro “crystal”
Add distro “dashing”
Add distro “eloquent”
Add distro “foxy”
Skip end-of-life distro “groovy”
Skip end-of-life distro “hydro”
Skip end-of-life distro “indigo”
Skip end-of-life distro “jade”
Add distro “kinetic”
ERROR: error loading sources list:
(https://raw.githubusercontent.com/ros/rosdistro/master/kinetic/distribution.yaml)>
jiang@ubuntu:~$ rosdep update
reading in sources list data from /etc/ros/rosdep/sources.list.d
Hit https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/osx-homebrew.yaml
Hit https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/base.yaml
Hit https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/python.yaml
Hit https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/ruby.yaml
Hit https://raw.githubusercontent.com/ros/rosdistro/master/releases/fuerte.yaml
Query rosdistro index https://raw.githubusercontent.com/ros/rosdistro/master/index-v4.yaml
Skip end-of-life distro “ardent”
Skip end-of-life distro “bouncy”
Skip end-of-life distro “crystal”
Add distro “dashing”
Add distro “eloquent”
Add distro “foxy”
Skip end-of-life distro “groovy”
Skip end-of-life distro “hydro”
Skip end-of-life distro “indigo”
Skip end-of-life distro “jade”
Add distro “kinetic”
Skip end-of-life distro “lunar”
Add distro “melodic”
Add distro “noetic”
updated cache in /home/jiang/.ros/rosdep/sources.cache
jiang@ubuntu:~$
解决方案：
1.更换为手机4G热点
2.更换为阿里的源
3.增加TIMEOUT时间
sudo gedit /usr/lib/python2.7/dist-packages/rosdep2/gbpdistro_support.py
搜索DOWNLOAD_TIMEOUT=45.0
4.安装python
5.安装python-dep
更新成功！