ghosts/inventories/fetch issue

[Robert Collins]

Fetching from a repository with ghosts on its RHS ancestory can fail
when a delta is fetched but its compression parent is inaccessible.

This requires that a text is compressed onto a revision that the target
repo does not have.
e.g.
T:[Ghost-in-target]

It also requires that ghost-in-target is not a ghost in the source.

And that the ghost won't be filled by normal fetch.

So:
source rev graph:
T:[Common]
Common:[ghost-in-target]
ghost-in-target:[]

source file compression graph:
T:[ghost-in-target]

This requires that common's inventory refer to ghost-in-target.

target rev graph:
Common:[ghost-in-target]

Now, this is actually invalid in bzr itself, because we determine all
the text revs we need by checking the inventory of common and would find
ghost-in-target and have caused an error cloning.

However, bzr-svn does something that can cause this.

bzr should auto-reconver from this situation as the source repo has the
ghost in question - it could dynamically grab the extra needed
revisions.

See also bug 250480 which is closely related.

-Rob
 affects bzr

--
GPG key available at: <http://www.robertcollins.net/keys.txt>.

[Jelmer Vernooij (jelmer)]

Dupe of 336749 (or the other way around) ?