#1477 [python] Imports are detected as CPD duplicates

[Lasse Schuirmann]

To reproduce, run CPD for python over https://github.com/coala-analyzer/coala/ and you'll get lots of import duplicates.

(I ran coala -I -b CPDBear -S language=py --files="*.py,coalib/**/*.py,tests/**/*.py" with coala 0.6, coala-bears 0.2, pmd 5.4.1 on the repository master. Most results are false positives.)