This appears to be the culprit:

https://github.com/mongodb/mongo/blob/r3.1.9/src/mongo/s/grid.cpp#L110

    auto balSettingsResult =
        grid.catalogManager(txn)->getGlobalSettings(txn, SettingsType::BalancerDocKey);
    if (!balSettingsResult.isOK()) {
        warning() << balSettingsResult.getStatus();
        return false;
    }

It should not always return false on not OK status. If the status is ErrorCodes::NoMatchingDocument, then it should return true since the absence of the document means that the default behavior should be followed.