Check for ipython version since imports are different for 0.10 and 0.11
shell and rshell will try to import the < 0.11 path, if that fails it tries the > 0.10 path.
An option would be to check for the version and be more explicit:
In : import IPython
In : IPython.version
0.11 requires py2.6 or later, changed how ipython is embedded.