Catch urllib's HTTPException and give a meaningful error message to the user. Usually urllib only throws HTTPError exceptions, which already are a subclass of IOError.

#!/bin/sh

unset HGUSER
EMAIL="My Name <myname@example.com>"
export EMAIL

hg init test
cd test
touch asdf
hg add asdf
hg commit -d '1000000 0' -m commit-1
hg tip