Merge pull request #910 from Gabriel439/patch-1

Fix `??` in Nix warning message

scripts/install-nix-from-closure.sh

@@ -25,7 +25,7 @@ echo "performing a single-user installation of Nix..." >&2
 
 if ! [ -e $dest ]; then
     cmd="mkdir -m 0755 $dest && chown $USER $dest"
-    echo "directory $dest does not exist; creating it by running ‘$cmd’ using sudo" >&2
+    echo "directory $dest does not exist; creating it by running '$cmd' using sudo" >&2
     if ! sudo sh -c "$cmd"; then
         echo "$0: please manually run ‘$cmd’ as root to create $dest" >&2
         exit 1