It is finally time to freeze the bundle2 format! To do so we:
- rename HG2Y to HG20,
- drop "b2x:" prefix from all part names,
- rename capability to "bundle2-exp" to "bundle2"
- rename the hook flag from 'bundle2-exp' to 'bundle2'
The source information can, should be applied once when opening the transaction
for the pull. This will lets element processed within a bundle2 be aware of them
and open the door to running a set of hooks when closing this pull transaction.
This is similar to what is done in server's unbundle call.
The transaction is now carrying hook-related informations. So we use it to
retrieve the `node` argument. This will also carry around all kinds of other useful
informations (like: "are we in a bundle2 processing")
A bundle2 may contain multiple parts adding changegroups, in which case there
are multiple operation records for changegroups, each with its own return
value. Those multiple return values are aggregated in a single cgresult value
for the whole operation.
As can be seen in the associated test case, the situation with hooks is not
really the best, but without deeper thoughts and changes, we can't do much
better. Hopefully, things will be improved before bundle2 is enabled by default.
In the meanwhile, multiple changegroups is not expected to be in widespread
use, and even less expected to be used for pushes. Also, not many clients
cloning or pulling bundle2 with multiple changesets are not expected to have
changegroup hooks anyways.
