Allow autoreloading of `python -m custom_module runserver`

[Moriyoshi Koizumi]

The original fix [1] only attempted to deal with -m foo.bar where bar is a package and __main__.py exists under foo/bar.

When a dotted name for a module (for example, foo.bar.baz where baz.py resides under foo/bar) is specified like -m foo.bar.baz, the resulting arguments end up being -m foo.bar, which is uncalled for.

[1] ​https://github.com/django/django/commit/ec6d2531c59466924b645f314ac33f54470d7ac3

Fixed detection when started non-django modules with "python -m" in autoreloader.

[Moriyoshi Koizumi]

Patch

[Mariusz Felisiak]

It doesn't work in Django 3.1 so I would not call it a regression.

Can you send PR via GitHub?

[William Schwartz]

Looks fine. The one change I'd make is that I'd change

modspec.name.split(".")[-1] == "__main__"

to

modspec.name == "__main__" or modspec.name.endswith(".__main__")

to avoid dumb corner cases like a module named foo.my__main__ (which is how ​runpy.py itself deals with it).

[Moriyoshi Koizumi]

It doesn't work in Django 3.1 so I would not call it a regression.
Can you send PR via GitHub?

I put manage.py under some package like foo/bar/manage.py and run it like -m foo.bar.manage runserver .... This used to run perfectly on 3.1.

[Moriyoshi Koizumi]

​https://github.com/django/django/pull/14311

[Mariusz Felisiak]

Replying to Moriyoshi Koizumi:

I put manage.py under some package like foo/bar/manage.py and run it like -m foo.bar.manage runserver .... This used to run perfectly on 3.1.

Can you attach a sample project? It raises ModuleNotFoundError for me.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 9e4780de:

Fixed #32669 -- Fixed detection when started non-django modules which aren't packages with "python -m" in autoreloader.