[bug#39156] Test case for the patch

[Jakub Kądziołka]

I realized that I was somewhat unclear on what benefit this patch
brings. Without the patch, compiling any nim programs is broken, for
example:

~/tmp$ cat > hello.nim
echo("Hello")
~/tmp$ ~/guix/pre-inst-env guix environment --ad-hoc nim -- nim c
hello.nim
Hint: used config file
'/gnu/store/k19xvhqgh3x0f7ax25r15l5bw16lzism-nim-0.17.2/config/nim.cfg'
[Conf]
Hint: system [Processing]
Hint: hello [Processing]
CC: hello
Error: invocation of external compiler program failed. File exists
Additional info: Could not find command: '/gnu/st'. OS error: No such
file or directory 17