subrepos: recursive status/diff with ui.commitsubrepos=True

[Matt Mackall]

On Fri, 2011-12-02 at 12:54 +0000, David.Sedlock at lantiq.com wrote:
> Hi everybody,
> 
> We (Lantiq) would like to have an option to turn on recursive subrepo
> behavior. A good name for the option would be "recursesubrepos" though
> we could live with "commitsubrepos".

The latter is definitely off the table.

> We might agree with the statement "In general, we shouldn't put any
> major behavior changes under config settings", but would still argue
> that we are dealing with two systematically different usage models and
> having a convenient way to switch the non-default model on would be
> valuable.

> The option would be purely a user convenience (saves adding --subrepos
> all the time) and, in the transitional period leading up to full
> support for subrepos, would be clearly documented as USER BEWARE.
> Given that the default behavior is now clearly non-recursive (which
> wasn't clear before), and that the user goes against this with an
> explicit choice, we don't see that problems arising from the use of
> commands that do not yet support subrepos together with those that do
> is a decisive objection.

I'm extremely reluctant to spend effort working on supporting a
dichotomy that we should instead be eliminating. But I've found another
take on it that I think will work:

[experimental]
subrepo = True

(read as "enable the under-development features of subrepos")

The plan here is that we'll stage a bunch of features to enable
consistent recursive subrepos and once testers are fairly satisfied that
the given batch is reasonable, we'll migrate it into the default
behavior. Then we'll start adding new features under the same flag.

-- 
Mathematics is the supreme nostalgia of our time.