Location of the command is not updated after installing a package with executables in virtualenv (only in Python 2)

[irushchyshyn]

• Pip version: 9.0.1
• Python version: 2.7
• Operating system: Fedora 25

Description:

When one installs any package with an executable in a virtualenv using pip, the location of the executable is not updated in the hash right away. It gets updated only after reactivating the virtualenv or running hash -r to make shell forget all remembered locations.

The issue has already been reported in virtualenv (pypa/virtualenv#41), and hash -r is the only solution so far. Should not pip update the locations?

The issue applies only for Python2. I am using pytest as an example below:

What I've run:

$ virtualenv vv
Installing setuptools, pip, wheel...done.
$ . vv/bin/activate
(vv) $ py.test --version
This is pytest version 2.9.2, imported from /usr/lib/python2.7/site-packages/pytest.pyc
(vv) $ pip install pytest
...
Successfully installed py-1.4.33 pytest-3.0.7
(vv) $ which pytest
~/vv/bin/pytest
(vv) $ py.test --version
This is pytest version 2.9.2, imported from /usr/lib/python2.7/site-packages/pytest.pyc
(vv) $ ~/vv/bin/pytest --version
This is pytest version 3.0.7, imported from /home/ishcherb/vv/lib/python2.7/site-packages/pytest.pyc
(vv) $ pip --version
pip 9.0.1 from /home/ishcherb/vv/lib/python2.7/site-packages (python 2.7)
(vv) $ hash -r 
(vv) $ py.test --version
This is pytest version 3.0.7, imported from /home/ishcherb/vv/lib/python2.7/site-packages/pytest.pyc

[chrahunt]

We're tracking a help message update in #6863 that would narrow the window on these sorts of edge cases. There also doesn't seem to be a way for a non-shell-function to actually perform the rehash. I will close this issue eagerly in favor of #6863 (since we can't implement the hash update directly ourselves).