Provide a way to skip sys.exit() when using call_command()

[Claude Paroz]

When running a management command from Python code with call_command, any CommandError raised in the execute method will call sys.exit(1). This is not always desirable, so we should provide a way to call call_command without this flaw.

This should also allow us to fix issues like #10200 painlessly.

[Claude Paroz]

Add raise_on_error option

[Claude Paroz]

Alternative solution without additional parameter

[Claude Paroz]

After discussion on #django-dev, added a new patch that does not add any new parameter to call_command, but move sys.exit(1) higher in the calling stack so that it is not used with call_command. Only commands run from command line will reach exit().

[Claude Paroz]

Patch 2 + complementary docs

[Anssi Kääriäinen]

LGTM

[Claude Paroz <claude@…>]

In [f2b6763ad7cb281ca8699a9c3d532a82f965be4f]:

Fixed #18387 -- Do not call sys.exit during call_command.

Moved sys.exit(1) so as failing management commands reach it
only when running from command line.