dns: add comment explaining the purpose of `any_removed`

(cherry picked from commit 4d1ecd8d6dbe6666f9005950a95a6ba8321e653c)
(cherry picked from commit 01b4040a7ad6f0b8c4aad1aabe4827841df2fe1e)

1 files changed, 7 insertions, 1 deletions

diff --git a/src/core/dns/nm-dns-manager.c b/src/core/dns/nm-dns-manager.c
index 566f3d6626..bdf6fe6580 100644
--- a/src/core/dns/nm-dns-manager.c
+++ b/src/core/dns/nm-dns-manager.c
@@ -1951,8 +1951,14 @@ nm_dns_manager_set_ip_config(NMDnsManager         *self,
 
     if (!ip_data) {
         ip_data = _dns_config_ip_data_new(data, addr_family, source_tag, l3cd, ip_config_type);
-        if (!any_removed)
+        if (!any_removed) {
+            /* `any_removed` tracks whether we deleted any ip_data. If that happened,
+             * we already compared the old and new l3cds and set `changed` accordingly.
+             * Here we only need to set `changed` if we are adding a new ip_data without
+             * removing the old one.
+             */
             changed = TRUE;
+        }
     } else {
         ip_data->ip_config_type = ip_config_type;
         changed                 = TRUE;