diff --git a/contrib/python3-whitelist b/contrib/python3-whitelist
--- a/contrib/python3-whitelist
+++ b/contrib/python3-whitelist
@@ -430,6 +430,7 @@
 test-ssh-proto.t
 test-sshserver.py
 test-stack.t
+test-status-inprocess.py
 test-status-rev.t
 test-status-terse.t
 test-strip-cross.t
diff --git a/tests/test-status-inprocess.py b/tests/test-status-inprocess.py
--- a/tests/test-status-inprocess.py
+++ b/tests/test-status-inprocess.py
@@ -1,12 +1,24 @@
 #!/usr/bin/env python
 from __future__ import absolute_import, print_function
 
+import sys
+
 from mercurial import (
     commands,
     localrepo,
     ui as uimod,
 )
 
+print_ = print
+def print(*args, **kwargs):
+    """print() wrapper that flushes stdout buffers to avoid py3 buffer issues
+
+    We could also just write directly to sys.stdout.buffer the way the
+    ui object will, but this was easier for porting the test.
+    """
+    print_(*args, **kwargs)
+    sys.stdout.flush()
+
 u = uimod.ui.load()
 
 print('% creating repo')