Real fix for the duplicate items in ng-repeat within bs-popover

If your popover lacks a hasContent() function, Bootstrap will end up calling
the content() function twice, and in the case of bs-popover, this would result
in a redundant $compile.

This doesn't necessarily produce any ill effects, but if your bs-popover
partial contained an ng-repeat, the ng-repeat would be replicated once
for every element in the collection.

For example, this:

  Controller:
  ```$scope.things = [{name: "A"}, {name: "B"}, {name: "C"}];```

  Partial:
```
<div>
 This is my popover!
  <ul>
     <li ng-repeat="thing in things">{{thing.name}}</li>
  </ul>
</div>
```

*Output:*
  
 This is my popover!
   - A
   - A
   - A
   - B
   - B
   - B
   - C
   - C
   - C

*Expected Output:*

This is my popover!
   - A
   - B
   - C