To not interfere with other qemu_nbd_popen() calls in same test.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.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 00be68eca3..4e758308f2 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -296,7 +296,9 @@ def qemu_nbd_list_log(*args: str) -> str:
 @contextmanager
 def qemu_nbd_popen(*args):
     '''Context manager running qemu-nbd within the context'''
-    pid_file = file_path("pid")
+    pid_file = file_path("qemu_nbd_popen-nbd-pid-file")
+
+    assert not os.path.exists(pid_file)
 
     cmd = list(qemu_nbd_args)
     cmd.extend(('--persistent', '--pid-file', pid_file))
@@ -314,6 +316,8 @@ def qemu_nbd_popen(*args):
             time.sleep(0.01)
         yield
     finally:
+        if os.path.exists(pid_file):
+            os.remove(pid_file)
         log('Kill NBD server')
         p.kill()
         p.wait()
-- 
2.29.2