[TW-1600] Filtering "regressions"(?) in task-2.4.3, task-2.4.4

_Ralph Bean on 2015-04-21T14:33:55Z says:_

Here's an example of one. In previous versions of taskwarrior, the filter at the end would match only one task, but with task-2.4.3 it matches all three tasks.

```
(taskw)❯ task add foobar1
task adCreated task 742.
The project 'unsorted' has changed. Project 'unsorted' is 66% complete (1 of 3 tasks remaining).
(taskw)❯ task add foobar2
Created task 743.
The project 'unsorted' has changed. Project 'unsorted' is 50% complete (2 of 4 tasks remaining).
(taskw)❯ task add foobar+
Created task 744.
The project 'unsorted' has changed. Project 'unsorted' is 40% complete (3 of 5 tasks remaining).
```

```
(taskw)❯ task proj:unsorted
[task next proj = unsorted]

id age project description urg
742 11s unsorted foobar1 1
743 8s unsorted foobar2 1
744 5s unsorted foobar+ 1

3 tasks

❯ task description.contains:"foobar+"
[task next description ~ 'foobar+']

id age project description urg
742 18s unsorted foobar1 1
743 15s unsorted foobar2 1
744 12s unsorted foobar+ 1

3 tasks
```