systemctl/core: ignore masked units in preset-all

With any masked unit that would that would be enabled by presets, we'd get:

test@rawhide $ sudo systemctl preset-all
Failed to execute operation: Unit file is masked.

test@rawhide $ sudo systemctl --root=/ preset-all
Operation failed: Cannot send after transport endpoint shutdown

Simply ignore those units:

test@rawhide $ sudo systemctl preset-all
Unit xxx.service is masked, ignoring.

1 files changed, 8 insertions, 2 deletions

diff --git a/src/shared/bus-util.c b/src/shared/bus-util.c
index c8092e0e5..800657ccd 100644
--- a/src/shared/bus-util.c
+++ b/src/shared/bus-util.c
@@ -2206,11 +2206,17 @@ int bus_deserialize_and_dump_unit_file_changes(sd_bus_message *m, bool quiet, Un
                 if (!quiet) {
                         if (streq(type, "symlink"))
                                 log_info("Created symlink from %s to %s.", path, source);
-                        else
+                        else if (streq(type, "unlink"))
                                 log_info("Removed symlink %s.", path);
+                        else if (streq(type, "masked"))
+                                log_info("Unit %s is masked, ignoring.", path);
+                        else
+                                log_notice("Manager reported unknown change type \"%s\" for %s.", type, path);
                 }
 
-                r = unit_file_changes_add(changes, n_changes, streq(type, "symlink") ? UNIT_FILE_SYMLINK : UNIT_FILE_UNLINK, path, source);
+                r = unit_file_changes_add(changes, n_changes,
+                                          unit_file_change_type_from_string(type),
+                                          path, source);
                 if (r < 0)
                         return r;
         }