os.walk has an error handling mechanism because it goes through a
collection of files, so it's nice to have, for example, a function
applied if errors appear in some of those files.

As this operation is applicable only to one file, this is not useful at
all: if you want to catch the error, just do it.

Regarding the type of error, note that you can use the mechanism tiran
shows below (if err.errno equals errno.EPERM).

In any case, this bug is not applicable any more.