FFV1 & mencoder: "chroma shift parameters 7 0 are invalid"

[peter_b]

[PROBLEM]
Trying to decode a 10 bpc (bits-per-component) FFV1 file with mencoder (pix_fmt = yuv422p10le).
(On Debian 9, with mencoder installed from default repositories - version: 2:1.3.0-6. Files were created with Virtualdub2 build 43385)

I get an empty output video file and the following error message:

[ffv1 @ 0x7f81ea258ae0]chroma shift parameters 7 0 are invalid
Error while decoding frame!

I've found only 1 appearance of this error message (by "Domin W." on StackOverflow):

"when I try to decode packet with avcodec_send_packet/avcodec_receive_frame functions I get an error 'chroma shift parameters 7 0 are invalid'"

[SOLUTION]
To be continued...