Fix duplicate path detection

[pavel-kirienko]

Fix #60

@PetervdPerk-NXP can you please verify this? This is how you can deploy this version locally for testing:

pip install git+https://github.com/UAVCAN/pydsdl@issue-60

[coveralls]

Pull Request Test Coverage Report for Build 37392942

• 10 of 10 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 37139568:	0.0%
Covered Lines:	3343
Relevant Lines:	3343

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💛 - Coveralls

[PetervdPerk-NXP]

It's working now

hovergames@hovergames:~/uavcan$ yakut compile  ./public_regulated_data_types/uavcan  ./public_regulated_data_types/reg 
hovergames@hovergames:~/uavcan$ 

Thanks!