don't color engine tracebacks in tests

IPython/parallel/tests/__init__.py

@@ -85,7 +85,11 b" def add_engines(n=1, profile='iptest', total=False):"
     eps = []
     for i in range(n):
         ep = TestProcessLauncher()
-        ep.cmd_and_args = ipengine_cmd_argv + ['--profile=%s'%profile, '--log-level=50']
+        ep.cmd_and_args = ipengine_cmd_argv + [
+            '--profile=%s' % profile,
+            '--log-level=50',
+            '--InteractiveShell.colors=nocolor'
+            ]
         ep.start()
         launchers.append(ep)
         eps.append(ep)