Path warnings when Matlab runs inside Docker container.

[benjamin-heasly]

When Matlab starts inside a Docker container, we often seen warnings about missing items on Matlab's path. For example, like this, from our Jenkins server:

< M A T L A B (R) >
Copyright 1984-2015 The MathWorks, Inc.
R2015b (8.6.0.267246) 64-bit (glnxa64)
August 20, 2015

[�Warning: Name is nonexistent or not a directory:
/usr/local/MATLAB/from-host/toolbox/matlab/appdesigner/appdesigner]� 
[�Warning: Name is nonexistent or not a directory:
/usr/local/MATLAB/from-host/toolbox/matlab/testframework/performance]� 
[�Warning: Name is nonexistent or not a directory:
...

These warnings happen when Matlab's pathdef.m refers to directories that are not present inside the Docker container. This can happen for user directories that exist on the host, but not inside the container. It can also happen for internal Matlab directories that differ between Matlab versions.

We think that these warnings are not harmful because we use ToolboxToolbox to reset the Matlab path right after these warnings occur, in startup.m.

We might be able to avoid these warnings by paring down the pathdef.m that we use inside the container. We would need to find a minimal set of folders that Matlab requires for basic functioning, and that exist in all Matlab versions. Finding this would take some trial and error -- if such a set even exists.