How to reproduce:
1. Install Unity along with WebGL support in some root subdirectory (e.g. "/Applications/Unity")
2. In Terminal, navigate to "/Applications/Unity/PlaybackEngines/WebGLSupport/BuildTools/Brotli"
3. ls -l to view permissions.
4. Notice that directory "python" has rwx permissions for Owner but none for Group or Other

Expected result: directory "python" should have read and execute permissions for Group and Other
Actual result: directory "python" has no permissions for Group and Other

on MacOS 10.13.4:
Reproducible with: 2018.1.0a6, 2018.1.6f1, 2018.2.0b9, 2018.3.0a2
Not reproducible with: 2017.4.6f1, 2018.1.0a5

Notes:
- Because of this issue, WebGL builds fail when Brotli compression is used. To repro, just create a new project, switch to WebGL, set Brotli compression and build;
- Workaround: in terminal, navigate to /Applications/Unity/PlaybackEngines/WebGLSupport/BuildTools/Brotli/" and type "sudo chmod 755 python";
- The same behavior can be seen on Linux. However, granting permissions to the python folder itself does not seem to be enough and it requires permissions for "bro.py" file.