Sometimes things go wrong, and the setup script doesn't do what the developer wants.
Distutils catches any exceptions when running the setup script, and print a simple error message before the script is terminated. The motivation for this behaviour is to not confuse administrators who don't know much about Python and are trying to install a package. If they get a big long traceback from deep inside the guts of Distutils, they may think the package or the Python installation is broken because they don't read all the way down to the bottom and see that it's a permission problem.
On the other hand, this doesn't help the developer to find the cause of the failure. For this purpose, the DISTUTILS_DEBUG environment variable can be set to anything except an empty string, and distutils will now print detailed information what it is doing, and prints the full traceback in case an exception occurs.
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