Deserialization error while initializing cnn_face_detection_model_v1 with dlib_face_recognition_resnet_model_v1

Expected Behavior

I'm trying to initialize dlib.cnn_face_detection_model_v1 using dlib_face_recognition_resnet_model_v1.dat (or mmod_human_face_detector.dat to double-check).

Current Behavior

When using dlib_face_recognition_resnet_model_v1.dat, dlib reports deserialization error. Trying the same with mmod_human_face_detector.dat yields no such error.

Steps to Reproduce

1) Download pre-trained models:

2) Try to initialize dlib.cnn_face_detection_model_v1:

$ python
Python 3.6.7 |Anaconda custom (64-bit)| (default, Oct 23 2018, 19:16:44)
[GCC 7.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import dlib
>>> dlib.cnn_face_detection_model_v1('dlib_face_recognition_resnet_model_v1.dat')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
RuntimeError: An error occurred while trying to read the first object from the file dlib_face_recognition_resnet_model_v1.dat.
ERROR: Unexpected version found while deserializing dlib::loss_mmod_.
>>> dlib.cnn_face_detection_model_v1('mmod_human_face_detector.dat')
<dlib.cnn_face_detection_model_v1 object at 0x7f963a0348f0>

Information

Version: 19.17.0 (19.16.0 compiled with Clang 7.0.1 on Arch Linux fails, too)
Where did you get dlib: tried three options: installing from pip, from Arch Linux's AUR (https://aur.archlinux.org/packages/python-dlib/), installing from pip inside Anaconda environment.

Platform: 1) Arch Linux + dlib from AUR/pip (with Python 3.7.2)

LSB Version:    1.4
Distributor ID: Arch
Description:    Arch Linux
Release:        rolling
Codename:       n/a

2) Ubuntu 18.04 + dlib from pip within Anaconda environment (with Python 3.6.7)

Distributor ID: Ubuntu
Description:    Ubuntu 18.04.1 LTS
Release:        18.04
Codename:       bionic

Compiler: When building from source (Arch AUR), GCC 8.2.1. When installing from pip, no compiler is used.

davisking / dlib