Fix debug function when used inside function returning a value

[Tantrisse]

Hi,

The debug function sometimes cause problem when used inside function which return a value.

As an example, in the "update" function, we get the version via version=$(get_bin_version). In get_bin_version, we call as_user which return the bash output in the main stream.

But if debug is true, the debug function will print the result of debug "as_user: $1}" in the main stream and mess up the return value of as_user breaking badly the update function :

DEBUG: Invocation: python3 /app/projects/factorio/factorio-updater/update_factorio.py --for-version DEBUG: as_user: /app/projects/factorio/factorio/bin/x64/factorio --version |egrep '^Version: [0-9\.]+' |egrep -o '[0-9\.]+' |head -n 1}   
1.0.0 --package core-linux_headlessDEBUG: as_user: /app/projects/factorio/factorio/bin/x64/factorio --version |egrep '^Binary version: ' |egrep -o '[0-9]{2}'}                                                                                
64 --output-path DEBUG: as_user: mktemp -d -p /tmp factorio-update.XXXXXXXXXX}                                                                                                                                                                
/tmp/factorio-update.qV9meT6jn8 --verbose

We can see here the output of the debug function is mixed in.

This fix modify the debug function making it print the debug message in /dev/tty (the terminal directly), making the function itself not returning anything and so not messing up with any code calling it.

Tell me what you think about it, /dev/tty seems the right solution to me but you may have a better idea ?

[Tantrisse]

Ok, I'm closing for now, /dev/tty break all tests because they need the text to be in the output stream.

I'll try another way with (maybe output debug in the error stream >&2 ?)

Anyway, for now the tests fail in my machine because the docker image are missing some ARG and centos refuse to build because of too old make... (??)