Strange Django issue: Error: No module named cache —14 August 2012

Just now when running ./manage.py syncdb Django (1.4) gave a strange error:

`Error: No module named cache
`

What tha… Googled it, no help. A pip install -r pip.txt --upgrade made it work. Lucky! (Among other things it replaced my Django 1.4 installation in the virtualenv. I suspect that fixed it.)