I don't understand why this test never failed in the past, as we've had implicit imports (sympy calls the implicit, but they are called wildcard imports in PEP-8) in the `mechanics/__init__.py` for a long time. See:

https://github.com/sympy/sympy/blob/master/sympy/physics/mechanics/__init__.py#L15

Note that PEP-008 says:

"Implicit relative imports should never be used and have been removed in Python 3", but I don't think this refers to wildcard imports.

http://www.python.org/dev/peps/pep-0008/#imports

Our wildcard imports here are perfectly valid. I don't understand why the code_quality test is against them.