Running ipython (2.7) with dev-python/pathlib-1.0.1-r1 results in the following error: Traceback (most recent call last): File "/usr/lib/python-exec/python2.7/ipython", line 4, in <module> from IPython import start_ipython File "/usr/lib64/python2.7/site-packages/IPython/__init__.py", line 49, in <module> from .terminal.embed import embed File "/usr/lib64/python2.7/site-packages/IPython/terminal/embed.py", line 15, in <module> from IPython.core.magic import Magics, magics_class, line_magic File "/usr/lib64/python2.7/site-packages/IPython/core/magic.py", line 22, in <module> from IPython.core import oinspect File "/usr/lib64/python2.7/site-packages/IPython/core/oinspect.py", line 40, in <module> from IPython.utils.text import indent File "/usr/lib64/python2.7/site-packages/IPython/utils/text.py", line 21, in <module> from pathlib2 import Path ImportError: No module named pathlib2 ipython3 (3.5) started properly. Emerging dev-python/pathlib-1.0.1-r2 fixed the problem with ipython2.