If --gdb and --valgrind are both defined, return an error.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 tests/qemu-iotests/iotests.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index 89099c13e6..b9f0ac0ddd 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -594,7 +594,11 @@ class VM(qtest.QEMUQtestMachine):
     def __init__(self, path_suffix=''):
         name = "qemu%s-%d" % (path_suffix, os.getpid())
         timer = 15.0 if not (qemu_gdb or qemu_valgrind) else None
-        super().__init__(qemu_prog, qemu_opts, wrapper=qemu_gdb,
+        if qemu_gdb and qemu_valgrind:
+            sys.stderr.write('Either use gdb or valgrind, not together\n')
+            sys.exit(1)
+        wrapper = qemu_gdb if qemu_gdb else qemu_valgrind
+        super().__init__(qemu_prog, qemu_opts, wrapper=wrapper,
                          name=name,
                          base_temp_dir=test_dir,
                          socket_scm_helper=socket_scm_helper,
-- 
2.30.2