bug#50433: shotcut 21.06.29 missing bin files

[Fulbert]

Hello,

shotcut 21.06.29 (guix ce65f2b) appears to have missing bin files. When 
trying to export a video, the status of the task is "failed" inside the 
GUI, and below is the debug message on the terminal.

[Debug  ] <MeltJob::start> 
"/gnu/store/qz8nr42ax7k3v0cysmh6afhmy93vvj82-shotcut-21.06.29/bin/melt-7 
-verbose -progress2 -abort xml:%2Ftmp%2Fshotcut-xNVrrX.mlt"
[Info   ] <AbstractJob::onFinished> job failed with 127

And here is the content of the bin directory :

$ ls -la $(dirname $(realpath $(which shotcut)))
total 3248
dr-xr-xr-x 2 root root    4096  1 janv.  1970 .
dr-xr-xr-x 4 root root    4096  1 janv.  1970 ..
-r-xr-xr-x 2 root root    1840  1 janv.  1970 shotcut
-r-xr-xr-x 2 root root    1401  1 janv.  1970 .shotcut-real
-r-xr-xr-x 2 root root 3308600  1 janv.  1970 ..shotcut-real-real