* YANG when statement in conjunction with grouping/uses/augment

* Several cases were not implemented fully according to RFC 7950
    * Do not extend default values if when statements evaluate to false
    * Do not allow edit-config of nodes if when statements evaluate to false (Sec 8.3.2)
    * If a key leaf is defined in a grouping that is used in a list, the "uses" statement MUST NOT have a "when" statement. (See 7.21.5)
  * See [yang uses's substatement when has no effect #218](https://github.com/clicon/clixon/issues/2$

test/test_augment.sh

@@ -199,11 +199,10 @@ if [ $BE -ne 0 ]; then
     fi
     new "start backend -s init -f $cfg"
     start_backend -s init -f $cfg
-
-    new "wait backend"
-    wait_backend
 fi
 
+new "wait backend"
+wait_backend
 
 if [ $RC -ne 0 ]; then
     new "kill old restconf daemon"
@@ -211,11 +210,11 @@ if [ $RC -ne 0 ]; then
 
     new "start restconf daemon"
     start_restconf -f $cfg
-
-    new "wait restconf"
-    wait_restconf
 fi
 
+new "wait restconf"
+wait_restconf
+
 # mandatory-leaf See RFC7950 Sec 7.17
 new "netconf set interface with augmented type and mandatory leaf"
 expecteof "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO<rpc $DEFAULTNS><edit-config><target><candidate/></target><config><interfaces xmlns=\"urn:ietf:params:xml:ns:yang:ietf-interfaces\">