Calling revlog.addgroup with an empty changegroup now raises RevlogError. The empty changegroup can be caused by remote servers dying soon after findincoming, and further code in pull assumes (correctly) that there are new changesets.

#!/bin/sh

hg init

echo "Is there an error message when trying to diff non-existing files?"
hg diff not found

echo "Is there an error message when trying to add non-existing files?"
hg add not found