fix: ipython import not required for ipythonx plugin

Author: satra

nipype/pipeline/plugins/ipythonx.py

@@ -5,11 +5,13 @@
 
 import sys
 
-from IPython import __version__ as IPyversion
+IPython_not_loaded = False
 try:
+    from IPython import __version__ as IPyversion
     from IPython.kernel.contexts import ConnectionRefusedError
 except:
-    pass
+    IPython_not_loaded = True
+
 
 from .base import (DistributedPluginBase, logger, report_crash)
 
@@ -18,6 +20,8 @@ class IPythonXPlugin(DistributedPluginBase):
     """
 
     def __init__(self, plugin_args=None):
+        if IPython_not_loaded:
+            raise ImportError('IPython parallel could not be imported')
         super(IPythonXPlugin, self).__init__(plugin_args=plugin_args)
         self.ipyclient = None
         self.taskclient = None