use domain api in sub shell.

le.sh

@@ -1041,6 +1041,7 @@ issue() {
           continue
         fi
         
+        (
           if ! source $d_api ; then
             _err "Load file $d_api error. Please check your api file and try again."
             return 1
@@ -1056,6 +1057,11 @@ issue() {
             _err "Error add txt for domain:$txtdomain"
             return 1
           fi
+        )
+        
+        if [[ "$?" != "0" ]] ; then
+          return 1
+        fi
         dnsadded='1'
       fi
     done