@jhale: a style remark (we try very hard to maintain the same 'code' style across all easyconfigs): please use one URL per line (and indent with 4 spaces), and I don't see a need for using `backup_url` (I think that was a trick to avoid very long lines?):

```python
source_urls = [
    'http://origin.releases.qt-project.org/qt4/source/',
    'http://master.qt-project.org/archive/qt/%(major_minor_version)s/%(version)s/',
```