`d:getetag` property has empty value in REPORT response

Taken from https://github.com/owncloud/ocis/issues/4712

### Steps
```bash
curl -XREPORT "https://localhost:9200/remote.php/dav/spaces" \
-d '




(name:"*share*" OR content:"share")

' \
-uadmin:admin -vk
```

### Actual
```xml

```

### Expected
```xml
"7d72a8365fd8c6ef6cba5c549d0b14a6"
```