Running Jenkins 2.79 on macOS 10.11.6 El Capitan, and also did a test setup on a macOS 10.10.5 Yosemite virtual machine.
Install was initially done with the official Jenkins package, and not via homebrew. Later I did another test install with homebrew and had the same problem.
I have had a lot of problems trying to get Jenkins running correctly on Mac. I have setup Jenkins on CentOS and really didn’t have to do much of anything.
With Jenkins on Mac it seems like it is a lot more all over the place in terms of basic default file location and user permissions.

I am trying to run a Project test that executes code written in Python and get a failure that seems to be resulting from this message:
/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/subprocess.py:1544: FileNotFoundError

There are a lot of sections in the startup that look like this:

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/subprocess.py:696: in run with Popen(*popenargs, **kwargs) as process:
/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/subprocess.py:950: in init restore_signals, start_new_session)

I am running this from a Freestyle Project that when it comes to the Build section is setup to run an Execute Shell command that calls my Python code using pytest
I have also tried to make sure that my Environment Variables contains the location of Python so that it can use it from PATH like the following:
PATH /Library/Frameworks/Python.framework/Versions/3.5/bin:/usr/bin:/bin:/usr/sbin:/sbin

The Jenkins setup on CentOS that has the same configuration and works by default without having to change any Jenkins settings. One difference I have noticed is that in the Environment Variables on the CentOS $ SHLVL runs with 3, while the Mac variable shows it running as 0

I have tried modifying the permissions on my Python installation, but so far have not had any luck. Has anyone else had a problem like this, or have any suggestions on what to try to correct this issue?