Run the top level module tests in a single process.

IPython/testing/iptest.py

@@ -187,8 +187,7 b' def make_runners():'
     else:
         runners['trial'] = IPTester('trial',['IPython'])
 
-    for m in modules:
-        runners[m] = IPTester(params=m)
+    runners['modules'] = IPTester(params=modules)
 
     return runners