ubuntu upgrade from 1.7.0 to 1.7.1 fails with missing 1.7.0 config

1) install 1.7.0
2) create a bucket and load some keys into it
3) attempt to upgrade to 1.7.1r-57
At this point the upgrade shows some errors. 1.7.1r-57 does get installed, however the previous config data from 1.7.0 wasn't transferred over

ubuntu@ip-10-84-202-81:~$ sudo dpkg -i membase-server-enterprise_x86_64_1.7.1r-57-ge726739.deb
(Reading database ... 29573 files and directories currently installed.)
Preparing to replace membase-server 1.7.0 (using membase-server-enterprise_x86_64_1.7.1r-57-ge726739.deb) ...

• Stopped Membase server
  Upgrading previous membase ... (1.7.0)
  Stopping previous membase ... (1.7.0)
• Stopped Membase server
  Saving previous membase config.dat ...
  Cleaning symlinks ...
  Unpacking replacement membase-server ...
  Setting up membase-server (1.7.1r) ...
  Upgrading from 1.7.0 ...
  /opt/membase/bin/mbupgrade -c /etc/opt/membase/1.7.0 -a yes
  Automatic mode: running without interactive questions or confirmations.
  Error: previous config directory incorrect: /etc/opt/membase/1.7.0
  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