Fix tests for IPython.testing

IPython/testing/plugin/show_refs.py

@@ -1,20 +1,20 b''
 """Simple script to show reference holding behavior.
 
 This is used by a companion test case.
 """
 from __future__ import print_function
 
 import gc
 
 class C(object):
    def __del__(self):
       pass
       #print 'deleting object...'  # dbg
 
 if __name__ == '__main__':
    c = C()
 
    c_refs = gc.get_referrers(c)
-   ref_ids = map(id,c_refs)
+   ref_ids = list(map(id,c_refs))
 
-   print('c referrers:',map(type,c_refs))
+   print('c referrers:',list(map(type,c_refs)))