diff --git a/mercurial/testing/__init__.py b/mercurial/testing/__init__.py
--- a/mercurial/testing/__init__.py
+++ b/mercurial/testing/__init__.py
@@ -25,7 +25,7 @@ def wait_file(path, timeout=10):
     timeout *= _timeout_factor()
     start = time.time()
     while not os.path.exists(path):
-        if time.time() - start > timeout:
+        if timeout and time.time() - start > timeout:
             raise RuntimeError(b"timed out waiting for file: %s" % path)
         time.sleep(0.01)