Investigate python>3.7 test failure (imageScene2D_test.py)

[k-dominik]

creating a dev environment with a Python version newer than 3.7 currently results in the following test hang:

  File "/.../vdev/lib/python3.8/site-packages/_pytest/main.py", line 268, in wrap_session
    session.exitstatus = doit(config, session) or 0
  File "/.../vdev/lib/python3.8/site-packages/_pytest/main.py", line 322, in _main
    config.hook.pytest_runtestloop(session=session)
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_hooks.py", line 265, in __call__
    return self._hookexec(self.name, self.get_hookimpls(), kwargs, firstresult)
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_manager.py", line 80, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_callers.py", line 60, in _multicall
    return outcome.get_result()
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_result.py", line 60, in get_result
    raise ex[1].with_traceback(ex[2])
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_callers.py", line 39, in _multicall
    res = hook_impl.function(*args)
  File "/.../vdev/lib/python3.8/site-packages/_pytest/main.py", line 347, in pytest_runtestloop
    item.config.hook.pytest_runtest_protocol(item=item, nextitem=nextitem)
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_hooks.py", line 265, in __call__
    return self._hookexec(self.name, self.get_hookimpls(), kwargs, firstresult)
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_manager.py", line 80, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_callers.py", line 60, in _multicall
    return outcome.get_result()
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_result.py", line 60, in get_result
    raise ex[1].with_traceback(ex[2])
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_callers.py", line 39, in _multicall
    res = hook_impl.function(*args)
  File "/.../vdev/lib/python3.8/site-packages/_pytest/runner.py", line 111, in pytest_runtest_protocol
    runtestprotocol(item, nextitem=nextitem)
  File "/.../vdev/lib/python3.8/site-packages/_pytest/runner.py", line 130, in runtestprotocol
    reports.append(call_and_report(item, "call", log))
  File "/.../vdev/lib/python3.8/site-packages/_pytest/runner.py", line 219, in call_and_report
    call = call_runtest_hook(item, when, **kwds)
  File "/.../vdev/lib/python3.8/site-packages/_pytest/runner.py", line 258, in call_runtest_hook
    return CallInfo.from_call(
  File "/.../vdev/lib/python3.8/site-packages/_pytest/runner.py", line 338, in from_call
    result: Optional[TResult] = func()
  File "/.../vdev/lib/python3.8/site-packages/_pytest/runner.py", line 259, in <lambda>
    lambda: ihook(item=item, **kwds), when=when, reraise=reraise
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_hooks.py", line 265, in __call__
    return self._hookexec(self.name, self.get_hookimpls(), kwargs, firstresult)
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_manager.py", line 80, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_callers.py", line 60, in _multicall
    return outcome.get_result()
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_result.py", line 60, in get_result
    raise ex[1].with_traceback(ex[2])
  File "/.../vdev/lib/python3.8/site-packages/pluggy/_callers.py", line 39, in _multicall
    res = hook_impl.function(*args)
  File "/.../vdev/lib/python3.8/site-packages/_pytest/runner.py", line 166, in pytest_runtest_call
    item.runtest()
  File "/.../vdev/lib/python3.8/site-packages/_pytest/unittest.py", line 327, in runtest
    self._testcase(result=self)  # type: ignore[arg-type]
  File "/.../vdev/lib/python3.8/unittest/case.py", line 736, in __call__
    return self.run(*args, **kwds)
  File "/.../vdev/lib/python3.8/unittest/case.py", line 676, in run
    self._callTestMethod(testMethod)
  File "/.../vdev/lib/python3.8/unittest/case.py", line 633, in _callTestMethod
    method()
  File ".../ilastik-meta/volumina/tests/imageScene2D_test.py", line 184, in testBasicImageRenderingCapability
    aimg = self.renderScene(self.scene)
  File ".../ilastik-meta/volumina/tests/imageScene2D_test.py", line 176, in renderScene
    s.joinRenderingAllTiles(viewport_only=False)
  File ".../ilastik-meta/volumina/volumina/imageScene2D.py", line 593, in joinRenderingAllTiles
    self._tileProvider.waitForTiles(sceneRectF)
  File ".../ilastik-meta/volumina/volumina/tiling/__init__.py", line 306, in waitForTiles
    for tile in tiles:
  File ".../ilastik-meta/volumina/volumina/tiling/__init__.py", line 287, in getTiles
    self.requestRefresh(rectF)
  File ".../ilastik-meta/volumina/volumina/tiling/__init__.py", line 319, in requestRefresh
    self._refreshTile(stack_id, tile_no, prefetch, layer_indexes)
  File ".../ilastik-meta/volumina/volumina/tiling/__init__.py", line 373, in _refreshTile
    transform *= self.tiling.data2scene