astropy/astropy — pull request #1423 by mhvk (2013-09-07 18:41:51+00:00)
Title: Ensure Angle subclass is conserved when changing unit

Currently, when changing unit on a `Longitude` or `Latitude`, and `Angle` is returned:
```
from astropy.coordinates import Angle, Longitude, Latitude
Longitude('120d').to('hourangle')
```
yields
```

```
This PR corrects that (and adds a regression test)