fix error message on `make test` when bison is not installed

diff --git a/run-tests.php b/run-tests.php
index c2052341b4eca9a2f79f85eb5dee035eb65b0e75..b62240e4f7ff5c34e22391dbbab6433352a08d05 100755 (executable)
--- a/run-tests.php
+++ b/run-tests.php
@@ -738,7 +738,7 @@ if ($just_save_results || !getenv('NO_INTERACTION')) {
                $failed_tests_data .= "Bundled Libtool:\n$libtool\n";
                $failed_tests_data .= "System Libtool:\n$sys_libtool\n";
                $failed_tests_data .= "Compiler:\n$compiler\n";
-               $failed_tests_data .= "Bison:\n". @shell_exec('bison --version'). "\n";
+               $failed_tests_data .= "Bison:\n". @shell_exec('bison --version 2>/dev/null'). "\n";
                $failed_tests_data .= "Libraries:\n$ldd\n";
                $failed_tests_data .= "\n";