The Python 2.5 "-m" command-line option allowed execution of a package
directly, by invoking the __init__.py module.

Python 2.6 no longer allows this.

This is a quite unfortunate regression, and I would urge the decision to
hobble it to be reconsidered.

Please see #2751.

Now, if someone was to provide a 2.7 rfe with associated patch that
implements this feature properly, and includes an explanation for why it
doesn't subtly break imports the way 2.5 does, that would be a
completely different story.

But it isn't as simple as just getting rid of the explicit check that
prevents packages from being executed.

I'm afraid it's all a bit opaque to an outsider like me. I've no idea 
what subtle breakage the feature was causing. I just saw it working 
quite nicely for me in 2.5 :)

If I recall correctly (it's been a while), the breakages were tied in
with relative imports - probably something like explicit relative
imports not working at all, and implicit relative imports appearing to
work, but resulting in incorrect module names and sys.modules entries
(similar to running a file from inside a package directly).

Doing "python -m package.__init__" instead of "python -m package" is
actually better behaved (although still a little odd - the
__init__ module code gets run once on the actual package import, and
then again as __main__).