inst.reason isn't alway in the form (errno, strerror)
urllib2.urlopen("foobar://foo") is an example
where inst.reason is a string
fix issue383
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