Regression: explicit relative imports in modules with __init__.py trigger E0402 relative-beyond-top-level

[jnsnow]

Issue #3528 and associated PR #3569 appear to have caused a regression in how modules with __init__.py are perceived.

If I install a dev copy of 4756b3c (origin/master as of writing) and revert this change, the explicit relative import works again.

Steps to reproduce

layout:

qemu/
  lib/
    __init__.py
    qmp.py
    machine.py
    qtest.py

qtest.py has an import statement like this:

from .machine import QEMUMachine

If CWD is qemu/lib and I execute:
> pylint qtest.py

2.4.4:

Your code has been rated at 10.00/10 (previous run: 9.82/10, +0.18)

2.5.0:

Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)

but 2.5.1:

qtest.py:24:0: E0402: Attempted relative import beyond top-level package (relative-beyond-top-level)

Current behavior

Relative imports trigger relative-beyond-top-level messages.

Expected behavior

As the relative imports function correctly during runtime, pylint should not produce an Error.

pylint --version output

Current setup:

pylint 2.5.1
astroid 2.4.1
Python 3.7.7 (default, Mar 13 2020, 21:39:43) 
[GCC 9.2.1 20190827 (Red Hat 9.2.1-1)]

More info:

From what I can tell, it seems as if the fact that I have an __init__.py is getting ignored (?), and my file is being processed as if it wasn't in a package. I seem to recall that what 'self.name' resolved to inside relative_to_absolute_name was surprisingly different, but naturally I didn't write it down...

[jnsnow]

@PCManticore I have one more facet of this to report that differs slightly from my above report. It might be the same as in #3651 ?

The structure I am prototyping for QEMU upstream is now:

python/
  qemu/
    core/
      __init__.py
      accel.py
      qmp.py
      machine.py
      qtest.py

i.e. qemu is a PEP420 namespace, core is the package.

__init__.py contains these lines:

from .accel import kvm_available, list_accel, tcg_available
from .machine import QEMUMachine
from .qmp import QEMUMonitorProtocol
from .qtest import QEMUQtestMachine, QEMUQtestProtocol

Starting from the containing directory, i.e. python/ (so the qemu/ namespace folder is in the CWD) WITHOUT the package installed to the current environment:

> pylint qemu

2.4.4: OK

2.5.0:

************* Module qemu
qemu/__init__.py:1:0: F0010: error while code parsing: Unable to load file qemu/__init__.py:
[Errno 2] No such file or directory: 'qemu/__init__.py' (parse-error)

2.5.1, 2.5.2, 2.5.3, 2.6.0: (Tested on 3.6. 2.6.0 was tested in 3.6, 3.7, and 3.8)

************* Module qemu.core
qemu/core/__init__.py:30:0: E0401: Unable to import 'qemu.core.accel' (import-error)
qemu/core/__init__.py:31:0: E0401: Unable to import 'qemu.core.machine' (import-error)
qemu/core/__init__.py:32:0: E0401: Unable to import 'qemu.core.qmp' (import-error)
qemu/core/__init__.py:33:0: E0401: Unable to import 'qemu.core.qtest' (import-error)

[clavedeluna]

I've attempted to reproduce this issue and can confirm that with pylint 2.15.4 the relative-beyond-top-level is not raised.