Due to the fix to the pull race, to avoid sending unnecessary
changesets, use changegroupsubset if possible.
This will increase the load on the server.
changegroup() has a problem when nodes which does not descend from a node
in <bases> are added to remote after the discovery phase.
If that happens, changegroup() won't send the correct set of nodes, ie.
some nodes will be missing.
To correct it we have to find the set of nodes that both remote and self
have (called <common>), and send all the nodes not in <common>.
This fix has some overhead, in the worst case it will re-send a whole branch.
A proper fix to avoid this overhead might be to change the protocol so that
the <common> nodes are sent (instead of the <bases> of the missing nodes).
Previously, fetch didn't really work when there were multiple named branches
in the repository. Now it tries to do the right thing(tm) in all situations.
With this change, "hg clone" looks like this:
% hg clone http://example.com/repo/big big
requesting all changes
adding changesets
adding manifests
adding file changes
added XXX changesets with XXX changes to XXX files
updating working directory
XXX files updated, XXX files merged, XXX files removed, XXX files unresolved
So the user sees
% hg clone http://example.com/repo/big big
requesting all changes
adding changesets
adding manifests
adding file changes
added XXX changesets with XXX changes to XXX files
updating working directory
while Mercurial is writing to disk to populate the working directory
With this change, "hg clone" looks like this:
% hg clone big big-work
updating working directory
XXX files updated, XXX files merged, XXX files removed, XXX files unresolved
This treats newly pulled changes as authoritative, and local changes as
the "satellite" changes.
The prior default behaviour is still available, via the --switch-parent
option.
