LGTM.com - false positive - Python: Module is imported with 'import' and 'import from'

**The analyser erroneously thinks the module is imported twice**

The specific case is within a `try`/`except ImportError` to handle older Python versions. These errors should not trigger if they are part of the same try/except block.

https://lgtm.com/projects/g/WoLpH/numpy-stl/snapshot/d42a4c10ac943a5789e77cba3c92ab0904ac975d/files/stl/base.py?sort=name&dir=ASC&mode=heatmap#x7cda6a9b22b9d912:1

```
try: # pragma: no cover
from collections import abc
except ImportError: # pragma: no cover
import collections as abc
```