Comment 5 for bug 1510015

click has the right dependencies here (click Depends: python3-click Depends: python3-apt Depends: libapt-pkg4.16). The problem is that unity-scope-click.prerm (the relevant bit of which is in fact generated by dh_click, so this isn't passing the buck) is calling click in a situation where click may be technically in an unconfigured state: in particular this is probably mid-way through upgrading the packages that form part of the g++ 5 transition between 15.04 and 15.10, so libapt-pkg and python-apt are temporarily in a rather sad state.

I don't think that strengthening dependencies is the answer here; instead, we need to make things more robust against being run in this kind of situation. The good news is that apt_pkg is only used in a few places in click, and they almost all tolerate it not being importable. The one exception is click.install, which originally imported apt_pkg because it used it to parse framework entries in manifests. That has since moved to click.framework, though, and the code there now copes with this situation.

It therefore looks as though we can just drop the apt_pkg bits from click.install and all will be well.