auth: Use MECH subsystem when logging error about skipping all passwo…

…rd databases

Otherwise it will assert-crash because all password databases were skipped.

src/auth/auth-request.c

@@ -1027,10 +1027,8 @@ void auth_request_verify_plain_continue(struct auth_request *request,
 	request->passdb = passdb;
 
 	if (passdb == NULL) {
-		auth_request_log_error(request, AUTH_SUBSYS_DB,
-			"All password databases were skipped for mechanism '%s'",
-				request->mech == NULL ? "<empty>"
-						      : request->mech->mech_name);
+		auth_request_log_error(request, AUTH_SUBSYS_MECH,
+			"All password databases were skipped");
 		callback(PASSDB_RESULT_INTERNAL_FAILURE, request);
 		return;
 	}
@@ -1208,10 +1206,8 @@ void auth_request_lookup_credentials_policy_continue(struct auth_request *reques
 	request->passdb = passdb;
 
 	if (passdb == NULL) {
-		auth_request_log_error(request, AUTH_SUBSYS_DB,
-			"All password databases were skipped for mechanism '%s'",
-				request->mech == NULL ? "<empty>"
-						      : request->mech->mech_name);
+		auth_request_log_error(request, AUTH_SUBSYS_MECH,
+			"All password databases were skipped");
 		callback(PASSDB_RESULT_INTERNAL_FAILURE, NULL, 0, request);
 		return;
 	}