package supervisor 3.0a8-1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 2

[Gonzalo Maldonado]

elg0nz@elg0nz-VirtualBox:~$ sudo apt-get install supervisor
Reading package lists... Done
Building dependency tree
Reading state information... Done
supervisor is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue [Y/n]? y
Setting up supervisor (3.0a8-1) ...
Starting supervisor: Traceback (most recent call last):
  File "/usr/bin/supervisord", line 9, in <module>
    load_entry_point('supervisor==3.0a8', 'console_scripts', 'supervisord')()
  File "/usr/lib/pymodules/python2.7/supervisor/supervisord.py", line 371, in main
    go(options)
  File "/usr/lib/pymodules/python2.7/supervisor/supervisord.py", line 381, in go
    d.main()
  File "/usr/lib/pymodules/python2.7/supervisor/supervisord.py", line 94, in main
    self.run()
  File "/usr/lib/pymodules/python2.7/supervisor/supervisord.py", line 104, in run
    self.options.openhttpservers(self)
  File "/usr/lib/pymodules/python2.7/supervisor/options.py", line 1039, in openhttpservers
    self.httpservers = self.make_http_servers(supervisord)
  File "/usr/lib/pymodules/python2.7/supervisor/options.py", line 1242, in make_http_servers
    return make_http_servers(self, supervisord)
  File "/usr/lib/pymodules/python2.7/supervisor/http.py", line 799, in make_http_servers
    from web import supervisor_ui_handler
  File "/usr/lib/pymodules/python2.7/supervisor/web.py", line 29, in <module>
    import meld3
  File "/usr/lib/pymodules/python2.7/meld3/__init__.py", line 2, in <module>
    from meld3 import parse_xml
  File "/usr/lib/pymodules/python2.7/meld3/meld3.py", line 27, in <module>
    from xml.etree.ElementTree import fixtag
ImportError: cannot import name fixtag
invoke-rc.d: initscript supervisor, action "start" failed.
dpkg: error processing supervisor (--configure):
 subprocess installed post-installation script returned error exit status 1
Processing triggers for python-support ...
Errors were encountered while processing:
 supervisor
E: Sub-process /usr/bin/dpkg returned an error code (1)

ProblemType: Package
DistroRelease: Ubuntu 11.04
Package: supervisor 3.0a8-1
ProcVersionSignature: Ubuntu 2.6.38-11.50-generic 2.6.38.8
Uname: Linux 2.6.38-11-generic i686
AptOrdering: supervisor: Configure
Architecture: i386
Date: Wed Oct 12 12:23:15 2011
ErrorMessage: subprocess installed post-installation script returned error exit status 2
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
PackageArchitecture: all
SourcePackage: supervisor
Title: package supervisor 3.0a8-1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 2
UpgradeStatus: Upgraded to natty on 2011-07-12 (92 days ago)

[Gonzalo Maldonado (elg0nz)]

jgj-barskdata's workaround solved this for me.