Fixed OSError "No such file or directory: None" and make IOError consistent. The None error occurs when the current working directory is no longer available, e.g. because it was removed in another shell.

#!/bin/sh

hg init
echo This is file a1 > a
hg add a
hg commit -m "commit #0" -d "1000000 0"
touch b
hg add b
rm b
hg commit -A -m"comment #1" -d "1000000 0"