Thanks for the tip Amaury. Following that lead, I see that distribute does indeed have a sandbox module which attempts to sandbox sys.modules, which can break the encodings modules. I'm going to address the issue in distribute first, but I like the proposals you've put forth.

I like the fourth one in particular, because it's always bugged me when I see other modules implementing #2, which is a workaround for the broader problem.

Is #4 the kind of issue that would require a PEP?