Cannot load libpython2.7.so.1.0

Starting yesterday, our builds on Docker image continuumio/miniconda:4.3.14 started failing with the following error:

/root/project/.tox/py27/bin/python2.7: error while loading shared libraries: libpython2.7.so.1.0: cannot open shared object file: No such file or directory

Based on this related post, I updated the Docker image to the latest continuumio/miniconda:4.6.14, but am still running into the same error. Docker images for python and for miniconda3 work just fine. This happened all of a sudden on two repos which use the same CircleCI settings. Does anyone have any idea of why we are getting the above error and what to do about it? Thanks.

The issue appears to result from an incompatibility between conda for python2.7 and the latest virtualenv 16.6.2, which was updated on conda-forge yesterday. Downgrading virtualenv to 16.0.0 fixed the issue.