按照官网更新git的命令：sudo add-apt-repository ppa:git-core/ppa
出现：sudo: add-apt-repository：找不到命令， 然后安装：sudo apt-get install software-properties-common
安装之后再执行sudo: add-apt-repository，之后出现：

Traceback (most recent call last):
  File "/usr/bin/add-apt-repository", line 95, in
    sp = SoftwareProperties(options=options)
  File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 109, in __init__
    self.reload_sourceslist()
  File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 599, in reload_sourceslist
    self.distro.get_sources(self.sourceslist)   
  File "/usr/lib/python3/dist-packages/aptsources/distro.py", line 93, in get_sources
    (self.id, self.codename))
aptsources.distro.NoDistroTemplateException: Error: could not find a distribution template for Uos/n/a


怎么办？