Add /bin to sudo secure_path

[nbonnotte]

see issue #524

cf. PR #525

[parente]

@nbonnotte Thanks for the PR. It looks like the tests failed waiting for a notebook server to startup in many cases. I'll retry them, but it's possible the change in start.sh broke something that needs local debugging.

[parente]

It'd be nice to keep the GRANT_SUDO option in this test to check that jovyan can run the sudo which jupyter command, and write another test (or parameterize this one) to check the case where the container launches as root without granting the user sudo.

[parente]

Replicating the test that is hanging:

~/p/docker-stacks ❯❯❯ docker run -it --rm --user root jupyter/base-notebook start.sh sudo which jupyter
Set username to: jovyan
usermod: no changes
Executing the command: sudo which jupyter
[sudo] password for jovyan:

The issue is that start.sh does exec sudo -E -H -u $NB_USER PATH=$PATH $cmd to switch to the $NB_USER which is jovyan by default. But then as jovyan, it's trying to execute the sudo which jupyter command given in the test or on the command line above.

When running the container as --user root with the start.sh script, the sudo test is implicit. I think we just need the new test to check which jupyter instead of sudo which jupyter. That or the test should not use start.sh and just run sudo which jupyter directly.

[nbonnotte]

@parente The tests are now passing