pyqgis - Which SAGA versions does QGIS 2.18.10 support?

Beginning with QGIS 2.18.10 the SagaAlgorithmProvider do not longer have a dictionary called supportedVersions. Previously, it looked like this:

supportedVersions = {"2.1.2": ("2.1.2", SagaAlgorithm212),

                     "2.1.3": ("2.1.3", SagaAlgorithm213),
                     "2.1.4": ("2.1.4", SagaAlgorithm214),
                     "2.2.0": ("2.2.0", SagaAlgorithm214),
                     "2.2.1": ("2.2.0", SagaAlgorithm214),
                     "2.2.2": ("2.2.2", SagaAlgorithm214),
                     "2.2.3": ("2.2.3", SagaAlgorithm214),
                     "2.3.0": ("2.3.0", SagaAlgorithm230),
                     "2.3.1": ("2.3.0", SagaAlgorithm230)}

Now it simply says:

if not version.startswith('2.3.'):
  ProcessingLog.addToLog(ProcessingLog.LOG_ERROR,
                         self.tr('Problem with SAGA installation
                                  unsupported SAGA version found.'))

So I would assume that now only SAGA versions starting with 2.3 are supported. However, in my QGIS GUI the Log Messages Panel tells me that SAGA version 2.3.1 is not supported (interestingly, you can use SAGA 2.3.1 in a custom application like RQGIS). So which SAGA versions are supported in QGIS 2.18.10?