No point in this. The purpose of that subroutine is to download the script and send it to stdout (the display), so the commands that follow ( | grep '^SCRIPTVER="v' | tr -cd '.0-9' ) could extract the version number from that output. That version number is being used later for comparison with the version number from the local copy of the script. The user don't need to download it, at least not at that point.
What if an old version of curl w/o ssl and redirect capabilties get "installed one way on another" the same way happened to you for wget?
That's also possible, but if you are so concerned about that, why don't you just hardcode the path to the stock binaries to ensure that exactly they will be used and nothing else? The stock curl in OS X is located at /usr/bin, as well as the stock wget in Linux. All it takes is two additional variables:
and so the corresponding lines will become:
if [[ -x $CURL ]]; then RSCRIPTVER='v'$($CURL -v --silent $GITHUB 2>&1 | grep '^SCRIPTVER="v' | tr -cd '.0-9') elif [[ -x $WGET ]]; then RSCRIPTVER='v'$($WGET $GITHUB -q -O - | grep '^SCRIPTVER="v' | tr -cd '.0-9') else return fi