[TW-1731] 'done' default filter surprisingly wide

_Daniel Shahaf on 2015-12-01T06:27:36Z says:_

Consider the following sequence:

```
% task add foo wait:1h
Created task 1.
% task add foo
Created task 2.
% task /foo/
ID Age Description Urg
2 2s foo 0
% task /foo/ done
Completed task 1 'foo'.
Completed task 2 'foo'.
Completed 2 tasks.
```

The user passed the same filter to `next` and to `done`, but a different set of tasks was affected each time. Concretely, I expected my `done` command to only affect the issues the report showed.

Now, `done` doesn't know what report the user viewed when she composed her regexp, and hence can't just "use an implicit `report.X.filter` filter, with `X` being the report the user was looking at". So perhaps `done` should present a per-task confirmation prompt, for tasks that were matched not by id or uuid but by regexp?

I'm not sure whether this is a known issue, but I haven't found a similar issue in jira history.