Catch ConnectionError on Py3.

This is a very boring possible fix for #442.

@joneskoo, do you might testing this branch out to see if it resolves your problem? Actually testing this is stupid-hard, you basically need to rely on a timing window.
Namely, imports (or faux-imports) are considered a "group", module-level constants are considered a "group" (that's why there were 2 lines separating them before).