Raise proper exceptions in python generators

[redixin]

Originating Project/Creator
Affected Component
Affected Architectures(s)
Related Issue(s)
Has Unit Tests (y/n)
Builds Without Errors (y/n)
Unit Tests Pass (y/n)
Documentation Included (y/n)

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Change Description

Change exception classes to less broad. E.g. Exception -> NotImplementedError

Rationale

Raising and catching `Exception' directly is not recommended in python. There are plenty built in exceptions to be used instead.

Testing/Review Recommendations

Please refer to python2 docs

https://python.readthedocs.io/en/v2.7.2/library/exceptions.html

Future Work

Consider migrating to python3, as python2 EOL is already reached.

[LeStarch]

Trying to force rerunning of checks that failed because devel was behind master.