in main

Fixed in crew (changeset 16276b1c0658)

I can reproduce this here with a clone of:
http://tx.downloads.xensource.com/xen-3.0-testing.hg
at revision 9614:0930c5a7c1e5.

Pulling from the above server (currently at 9679:7ae0f83cf355) gives the "abort: 
group to be added is empty!" error, but a new clone of the repository works ok.
I could provide you with a tarball of the local repo for debugging.

Now I can't reproduce it with pulling from these servers and it feels like the
hg server version was upgraded.

I've found that this problem occurs e.g. with the two following changes:
http://xenbits.xensource.com/xen-unstable.hg?cmd=changeset;node=6c43118bdba8d4316ddfffbea7a53f0b2f128ab3
http://xenbits.xensource.com/ext/xenppc-unstable.hg?cmd=filediff;node=91da9a1b7196b093c6b44906992bcbcad92b30a1;file=xen/include/asm-x86/mach-default/irq_vectors_limits.h

Both changesets remove a file during a merge, this may be the reason for an
empty changegroup to be transferred. Though this smells like a bug in the server
that it sends such a group or in the client that it requests it.

What about: "Transferred group is empty"?

On IRC, brendan reported yet another can't-talk-to-xensource-server problem,
this time manifesting as Thomas's "group to be added is empty" change from rev
4aab906517c6e.

We keep getting bitten by memory problems with the xensource.com server
manifesting themselves as mysterious complaints from the client.  This is a real
shame, as we have no insight into why the server keeps running out of memory,
and people show up making unhappy noises because the symptoms look like a
client-side problem.

I don't know quite how to beef up client-side error handling, but we could
really do with improving it :-(  It would also help to know why xensource.com's
server keeps plotzing.