fix multiple domains using domain alias

cm.sh

@@ -30,6 +30,7 @@
 # 2022-04-04  <axel.hahn@iml.unibe.ch>  Bugfix: copy key from csr folder to ~/.acme/
 # 2022-04-04  <axel.hahn@iml.unibe.ch>  added param "list-old"
 # 2022-04-07  <axel.hahn@iml.unibe.ch>  fix missing key in public_ensure before calling public_add too.
+# 2022-04-20  <axel.hahn@iml.unibe.ch>  fix multiple domains using domain alias
 # ======================================================================
 
 
@@ -409,7 +410,7 @@ function public_add(){
 
 		if [ -n "${CM_challenge_alias}" ] && ! echo "$_mydomain" | grep "${CM_certmatch}" >/dev/null
 		then
-			_params+="--challenge-alias ${CM_challenge_alias}"
+			_params+="--challenge-alias ${CM_challenge_alias} "
 		fi
 	done