[RFC] new format 1.12 (1.11?) enabling EOL & filtered views

[Ian Clatworthy]

Martin Pool wrote (28/10/08) in response to my latest EOL patch:

>> We still have some disagreement on whether this requires a format
>> bump or not. Martin and I think not, Robert thinks otherwise. I'll
>> let Robert and Martin argue that out because I lack the energy to
>> go over the issue yet again.
> 
> So, we did, and I agree we should stick with adding new formats when changing behaviour.   The bulk of this code is not tied to that decision, but I think that it does implicitly turn it on for all working trees, and we don't want that.   If we cut that out (and possibly do it in a plugin), I'd be ok to merge this.

As agreed between Robert and Martin above, a new working-tree
format is required to land EOL support. I also have a patch that
supports filtered views - think git's staging area but nicer - that
needs a working-tree format bump. I therefore want to introduce
a new format that I'm proposing to call 1.12.

To be more precise, I'd like to decouple the introduction of this
from the CHK format related work by doing the following:

1. Adding 2 new experimental formats called 1.12preview and
   1.12preview-rich-root respectively. These formats will be
   the same as their 1.9 counterparts except that the WT will
   be (the new) WT5, not WT4.

2. Resubmitting the content filtering patch so that it will
   only work with WT5 trees.

3. Submitting my filtered views patch.

4. When 2 & 3 are approved, rename 1.12preview to 1.12 (ditto
   the rich-root one) and remove the experimental flag.

If everything goes swimmingly and all that happens before 1.11RC,
we can call the format 1.11 instead of 1.12. :-)

How does that sound to everyone?

Ian C.