convert: clear the dirstate before a conversion, invalidate it afterwards Clearing it before the conversion protects us from whatever data were there (file copies in particular). Invalidating it after the conversion avoids writing a possibly inconsistent dirstate to disk.

Is there an error message when trying to diff non-existing files?
found: No such file or directory
not: No such file or directory
Is there an error message when trying to add non-existing files?
found: No such file or directory
not: No such file or directory