bug in mutable publish that could cause an IndexError when a writer is removed in Publish._connection_problem

[davidsarah]

"Traceback (most recent call last):
Failure: allmydata.mutable.common.NotEnoughServersError: (\"Publish ran out of good servers, last failure was:
[Failure instance: Traceback: <type 'exceptions.IndexError'>: list index out of range
/home/davidsarah/cloud-branch/support/lib/python2.6/site-packages/Twisted-12.0.0-py2.6-linux-i686.egg/twisted/internet/base.py:800:runUntilCurrent
/home/davidsarah/cloud-branch/support/lib/python2.6/site-packages/foolscap-0.6.3-py2.6.egg/foolscap/eventual.py:26:_turn
/home/davidsarah/cloud-branch/support/lib/python2.6/site-packages/Twisted-12.0.0-py2.6-linux-i686.egg/twisted/internet/defer.py:368:callback
/home/davidsarah/cloud-branch/support/lib/python2.6/site-packages/Twisted-12.0.0-py2.6-linux-i686.egg/twisted/internet/defer.py:464:_startRunCallbacks
(04:15:44) davidsarah: --- <exception caught here> ---\\n/home/davidsarah/cloud-branch/support/lib/python2.6/site-packages/Twisted-12.0.0-py2.6-linux-i686.egg/twisted/internet/defer.py:551:_runCallbacks
/home/davidsarah/cloud-branch/src/allmydata/mutable/publish.py:634:_push
/home/davidsarah/cloud-branch/src/allmydata/mutable/publish.py:651:push_segment
/home/davidsarah/cloud-branch/src/allmydata/mutable/publish.py:637:_push
/home/davidsarah/cloud-branch/src/allmydata/mutable/publish.py:773:push_everything_else
/home/davidsarah/cloud-branch/src/allmydata/mutable/publish.py:878:finish_publishing
/home/davidsarah/cloud-branch/src/allmydata/mutable/publish.py:886:_record_verinfo

I can reproduce this, at least on the cloud-branch, when I do a tahoe put --mutable shortly after the gateway has started.