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Since I have installed Ubuntu 15.10 I can no longer add ppa to my repository list:
@:~>sudo apt-add-repository ppa:git-core/ppa Cannot add PPA: 'ppa:~git-core/ubuntu/ppa'. ERROR: '~git-core' user or team does not exist.
Does somebody know what changed in 15.10? Maybe it is an issue with a proxy-server. I am behind a proxy server, but everything else like wget or apt-get is working with my current configuration.