test(retry_until): Return truthy when True, False with timeout raise=False

Author: tony

libtmux/test.py

@@ -88,8 +88,9 @@ def retry_until(
             if raises:
                 raise WaitTimeout()
             else:
-                break
+                return False
         time.sleep(interval)
+    return True
 
 
 def get_test_session_name(server, prefix=TEST_SESSION_PREFIX):