每当我尝试添加任何 PPA 来安装任何东西时，都会出现以下错误：
nikunj@nikunj-DL-H61MXE-V:~$ sudo add-apt-repository ppa:ravefinity-project/ppa
Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 326, in get_ppa_info
ret = get_ppa_info_from_lp(user, ppa)
File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 91, in get_ppa_info_from_lp
return get_info_from_lp(lp_url)
File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 87, in get_info_from_lp
return _get_https_content_py3(lp_url)
File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 101, in _get_https_content_py3
lp_page = urllib.request.urlopen(request, cafile=LAUNCHPAD_PPA_CERT)
File "/usr/lib/python3.4/urllib/request.py", line 148, in urlopen
raise ValueError('SSL support not available')
ValueError: SSL support not available
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/bin/add-apt-repository", …