Upgrade from 1.6.5.3/4 to 1.7.1 broken

Install 1.6.5.4 and upgrade to 1.7.1.

Get the following error:-

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Copying /etc/opt/membase/1.6.5.4/ns_1/config.dat.debsave
    cp /etc/opt/membase/1.6.5.4/ns_1/config.dat.debsave /opt/membase/var/lib/membase/config/config.dat
Copying /opt/membase/var/lib/membase/ip
    cp /opt/membase/var/lib/membase/ip /opt/membase/var/lib/membase/ip
Traceback (most recent call last):
  File "/opt/membase/bin/mbupgrade", line 435, in <module>
    main()
  File "/opt/membase/bin/mbupgrade", line 430, in main
    dbdir, buckets, dry_run=dry_run)
  File "/opt/membase/bin/mbupgrade", line 130, in upgrade
    dry_run=dry_run)
  File "/opt/membase/bin/mbupgrade", line 84, in copy_cfg
    shutil.copyfile(cfg, dst)
  File "/usr/local/lib/python2.7/shutil.py", line 68, in copyfile
    raise Error("`%s` and `%s` are the same file" % (src, dst))
shutil.Error: `/opt/membase/var/lib/membase/ip` and `/opt/membase/var/lib/membase/ip` are the same file
dpkg: error processing membase-server (--install):
 subprocess installed post-installation script returned error exit status 1
Processing triggers for ureadahead ...
Errors were encountered while processing:
 membase-server

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From /var/log/dpkg.log

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2011-08-11 14:23:27 upgrade membase-server 1.6.5.4 1.7.1
2011-08-11 14:23:27 status half-configured membase-server 1.6.5.4
2011-08-11 14:23:30 status unpacked membase-server 1.6.5.4
2011-08-11 14:23:30 status half-installed membase-server 1.6.5.4
2011-08-11 14:23:59 status triggers-pending ureadahead 0.100.0-4.1
2011-08-11 14:23:59 status half-installed membase-server 1.6.5.4
2011-08-11 14:24:11 status half-installed membase-server 1.6.5.4
2011-08-11 14:24:12 status unpacked membase-server 1.7.1
2011-08-11 14:24:12 status unpacked membase-server 1.7.1
2011-08-11 14:24:12 configure membase-server 1.7.1 1.7.1
2011-08-11 14:24:12 status unpacked membase-server 1.7.1
2011-08-11 14:24:12 status half-configured membase-server 1.7.1
2011-08-11 14:24:14 trigproc ureadahead 0.100.0-4.1 0.100.0-4.1
2011-08-11 14:24:14 status half-configured ureadahead 0.100.0-4.1
2011-08-11 14:24:15 status installed ureadahead 0.100.0-4.1
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The membase-server installation is right now left in half-configured state.