There is various version of this function that differ mostly by the way they
define the bundled set. The flexibility is now available in the outgoing object
itself so we move the complexity into the caller themself. This will allow use
to remove a good share of the similar function to obtains a changegroup in the
'changegroup.py' module.
An important side effect is that we stop calling 'computeoutgoing' in
'getchangegroup'. This is fine as code that needs such argument processing
is actually going through the 'exchange' module which already all this function
itself.
Bundle 2 is enable by default since 3.6 so we don't need this anymore.
The remaining use of 'experimental.bundle2-exp' are there to test legacy behavior
with bundle 1. Future patches will introduce a way outside of experimental to
test that.
Sometimes a txnclose or changegroup hook wants to iterate through all
the changesets in transaction: in that situation usually the revset
`$HG_NODE:` is used to select the revisions. Unfortunately this revset
sometimes may contain too many changesets because we don't have the
write lock while the hook runs newer changes may be added to
repository in the meantime.
That's why there is a need for extra variable carrying the information about
the last change in the transaction.
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.
