ipfs-test-lib: clarify and simplify shellquote()

Let's first add a comment to explain why the wrapper printf()
is needed.

Then let's replace the last instructions by quotes inside the
wrapper printf() first argument, and let's also put there the
eventual space so that we can remove the printf on the above
line.

License: MIT
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>

test/ipfs-test-lib.sh

@@ -28,8 +28,9 @@ shellquote() {
 	_space=''
 	for _arg
 	do
-		printf '%s' "$_space"
-		printf '%s' "$(printf '%s' "$_arg" | sed -e "s/'/'\\\\''/g; s/^/'/; s/\$/'/;")"
+		# On Mac OS, sed adds a newline character.
+		# With a printf wrapper the extra newline is removed.
+		printf "$_space'%s'" "$(printf "%s" "$_arg" | sed -e "s/'/'\\\\''/g;")"
 		_space=' '
 	done
 	printf '\n'