Don't try to import IPython when the python console is used.

With an explicit call to `./bin/isympy -c python` there is
no need to attempt importing IPython.

sympy/interactive/printing.py

@@ -293,7 +293,7 @@ def init_printing(pretty_print=True, order=None, use_unicode=None,
         except NameError:
             pass
 
-    if ip and pretty_print:
+    if ip and ip.__module__.startswith('IPython') and pretty_print:
         try:
             import IPython
             # IPython 1.0 deprecates the frontend module, so we import directly