Missing frames with -stream_loop and -f concat

[bogus]

Summary of the bug:
I'm creating a looped slideshow video out of jpeg images. The resulting video is missing the first image/frame in all repeated sections.

How to reproduce:

% ffmpeg -stream_loop 3 -r 1 -f concat -i list.txt out.mp4
ffmpeg version 4.4.1
built with gcc 11.2.0 (Rev1, Built by MSYS2 project)

For example, having list.txt like this:

file 'A.jpg'
file 'B.jpg'
file 'C.jpg'

The resulting video contains the following frames : ABC BC BC BC.
It's length is 3+(3-1)*3 = 9 frames, while it should be 3*4 = 12 frames.

See the attached archive.

Patches should be submitted to the ffmpeg-devel mailing list and not this bug tracker.