Mypy emits error on decorated property

[rpgoldman]

Note: if you are reporting a wrong signature of a function or a class in
the standard library, then the typeshed tracker is better suited
for this report: https://github.com/python/typeshed/issues

Please provide more information to help us understand the issue:

• Are you reporting a bug, or opening a feature request?
  Bug

• Please insert below the code you are checking with mypy,
  pymc3 -- see mypy error trying to check pymc3 #5560

• What is the actual behavior/output?
  I get this error message:

pymc3/model.py:672: error: Decorated property not supported

Not sure what this means or what to do about it.

• What is the behavior/output you expect?
  Either handling the decorated property or error message with suggestion for workaround.

• What are the versions of mypy and Python you are using?
  Do you see the same issue after installing mypy from Git master?
  This is with mypy from Git master: Testing with mypy 0.630+dev-581e514162797b531a01b86b5266b081e955d6df, commit 8c90771a20e4dff68e416d832c66b0df5dc2f958 from master.

• What are the mypy flags you are using? (For example --strict-optional)

mypy --show-traceback --ignore-missing-imports pymc3/

• If mypy crashed with a traceback, please paste
  the full traceback below.
  No crash.

Here is the code snippet (from model.py) that yields an error:

    @property
    @memoize(bound=True)
    def bijection(self):
        vars = inputvars(self.cont_vars)

        bij = DictToArrayBijection(ArrayOrdering(vars),
                                   self.test_point)

        return bij

[ilevkivskyi]

Duplicate of #1362

(Also I am not sure what is not clear in this error. See the original issue for how to work around this.)

[rpgoldman]

The original issue provides the work-around, but I didn't find that work-around obvious from the error message. Any reason why the error message shouldn't contain: "comment the @Property line for mypy to ignore" or something like that? Or somehow point to #1362, which has the magic answer?