I was trying something similar today "apt-get source -t quantal openvpn" and received the following error message:
$ apt-get source -t quantal openvpn
Reading package lists... Done
E: The value 'quantal' is invalid for APT::Default-Release as such a release is not available in the sources
only after adding deb lines from quantal (I'd previously only had deb-src lines) was I able to get the source of openvpn for quantal.
I was trying something similar today "apt-get source -t quantal openvpn" and received the following error message:
$ apt-get source -t quantal openvpn Release as such a release is not available in the sources
Reading package lists... Done
E: The value 'quantal' is invalid for APT::Default-
only after adding deb lines from quantal (I'd previously only had deb-src lines) was I able to get the source of openvpn for quantal.