It's not magic -- it's some form of crude error.

So first off what this does is, it expands to the expression:

    '-o /dev/null' '-o /dev/null '

Even if we remove the latter space by just using `{,}` instead of `{,\ }` curl still returns for me an error code 23 -- CURLE_WRITE_ERROR.

curl seems to interpret `'-o /wtf'` as a command to write to the file ` /wtf`, so this only makes sense if you have a directory called ` ` in the folder you're running from.

You can therefore do this correctly with:

    -o/dev/null{,}

and that correctly writes the contents to /dev/null without issuing a curl write error.