warn on detection of libzmq 3

IPython/parallel/__init__.py

@@ -16,6 +16,8 b' Authors:'
 #-----------------------------------------------------------------------------
 
 import os
+import warnings
+
 import zmq
 
 
@@ -26,6 +28,13 b" if os.name == 'nt':"
 elif zmq.__version__ < '2.1.4':
     raise ImportError("IPython.parallel requires pyzmq/0MQ >= 2.1.4, you appear to have %s"%zmq.__version__)
 
+if zmq.zmq_version() >= '3.0.0':
+    warnings.warn("""libzmq 3 detected.
+    It is unlikely that IPython's zmq code will work properly.
+    Please install libzmq stable, which is 2.1.x or 2.2.x""",
+    RuntimeWarning)
+
+
 from IPython.utils.pickleutil import Reference
 
 from .client.asyncresult import *

IPython/zmq/__init__.py

@@ -9,6 +9,8 b''
 # Verify zmq version dependency >= 2.1.4
 #-----------------------------------------------------------------------------
 
+import warnings
+
 minimum_pyzmq_version = "2.1.4"
 
 try:
@@ -23,3 +25,10 b' if pyzmq_version < minimum_pyzmq_version:'
                     minimum_pyzmq_version, pyzmq_version))
 
 del pyzmq_version
+
+if zmq.zmq_version() >= '3.0.0':
+    warnings.warn("""libzmq 3 detected.
+    It is unlikely that IPython's zmq code will work properly.
+    Please install libzmq stable, which is 2.1.x or 2.2.x""",
+    RuntimeWarning)
+