x262 produces a Variable Bitrate stream despite --nal-hrd cbr

[FranceBB]

Hi there,
x262 is producing a VBR stream despite setting CBR.

How to reproduce:

x262_64.exe "D:\Temp\AVS Script.avs" --mpeg2 --preset medium --level high --profile 422 --bitrate 50000 --vbv-maxrate 50000 --vbv-bufsize 17825792 --keyint 12 --bframes 2 --no-scenecut --open-gop --deblock -1:-1 --overscan show --colormatrix bt709 --range tv --transfer bt709 --colorprim bt709 --videoformat component --nal-hrd cbr --output-csp i422 --asm 1 --output "\\mibctvan000\Ingest\MEDIA\temp\raw_video.m2v"

pause

Video
Format                                   : MPEG Video
Format version                           : Version 2
Format profile                           : 4:2:2@High
Format settings                          : BVOP
Format settings, BVOP                    : Yes
Format settings, Matrix                  : Default
Format settings, GOP                     : M=3, N=12
Duration                                 : 3 min 20 s
Bit rate mode                            : Variable
Bit rate                                 : 53.5 Mb/s
Maximum bit rate                         : 50.0 Mb/s
Width                                    : 1 920 pixels
Height                                   : 1 080 pixels
Display aspect ratio                     : 16:9
Frame rate                               : 25.000 FPS
Standard                                 : Component
Color space                              : YUV
Chroma subsampling                       : 4:2:2
Bit depth                                : 8 bits
Scan type                                : Progressive
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 1.032
Time code of first frame                 : 00:00:00:00
GOP, Open/Closed                         : Open
GOP, Open/Closed of first frame          : Closed
Stream size                              : 1.25 GiB (100%)
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709