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.
1 files updated, 0 files merged, 0 files removed, 0 files unresolvedremoving babort: update spans branches, use 'hg merge' or 'hg update -C' to lose changes