Add revlog.parentrevs function. This allows one to walk the revision graph using only revision numbers, which can be faster than using revision hashes, especially for RevlogNG, where the parents of a revision are stored as revision numbers.

#!/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