wip(backend): allow set ip to null

lib/Ravada/VM.pm

@@ -676,11 +676,13 @@ sub display_ip($self, $value=undef) {
 }
 
 sub _set_display_ip($self, $value) {
-    my %ip_address = $self->_list_ip_address();
+    if (defined $value && length $value ) {
+        my %ip_address = $self->_list_ip_address();
 
-    confess "Error: $value is not in any interface in node ".$self->name
-    .". Found ".Dumper(\%ip_address)
-    if !exists $ip_address{$value};
+        confess "Error: $value is not in any interface in node ".$self->name
+        .". Found ".Dumper(\%ip_address)
+        if !exists $ip_address{$value};
+    }
 
     $self->_data( display_ip => $value );
 }

t/nodes/10_basic.t

@@ -1216,6 +1216,7 @@ sub test_display_ip($vm, $node, $set_localhost_dp=0) {
 
     $node->_data(display_ip => '');
     rvd_back->display_ip('') if $set_localhost_dp;
+    $vm->display_ip('')      if $set_localhost_dp;
 }
 
 sub test_nat($vm, $node, $set_localhost_natip=0) {