All actions in packaging.run need to respect a basic exit convention 0/1. 

This is important because pysetup will be used in automated scripts so the caller needs to know wether the call failed or succedeed. 

Example: pysetup install project => sys,exit(0 or 1)

fixed install in http://hg.python.org/cpython/rev/ebff46b232ed

Here’s a patch adding “return 1” after all errors, unifying the use of logging and cleaning up a few things (like moving KeyboardInterrupt handling from the _run function up to the main function).

BTW, some functions do not explicitly return 0, but this is okay: they will return None, which is a boolean false value, which is understood as 0 by sys.exit.

New changeset 998566bf7fba by Éric Araujo in branch 'default':
Let all pysetup actions return a meaningful 0 or 1 exit code (#12222).
http://hg.python.org/cpython/rev/998566bf7fba

I committed my patch, except for one change in the run action.  It returns the dist.Distribution instance, which is needed by test_uninstall and not trivial to fix.  I tried changing the code to use Distribution and command objects directly but suddenly the --prefix option was not respected, so I stopped after a few tries.

New changeset ab125793243f by Éric Araujo in branch 'default':
Fix return code of “pysetup run COMMAND” (closes #12222)
http://hg.python.org/cpython/rev/ab125793243f