bug#19865: tar-untar-buffer: should honor default-directory

[Stefan Monnier]

> It's the same as working in the shell:

That's also my impression.

> if you changed a directory, you need to go back before you operate on
> files, or risk operate on wrong files.

No: I changed directory specifically because I wanted to operate on
other files.  And I often don't go back.

>> I agree that having to be careful in which buffer we are when we read
>> a given variable because it might be buffer-local is a source of
>> maintenance headaches, but we have that all over the place in Elisp,
>> and we don't really have any "better solution".
> I don't really see a problem here that needs a solution.  A year from
> now no one will remember or understand why we use with-current-buffer
> in that place.

The comment explains why and the comment will still be there a year
from now.

The code takes a file name from one buffer and uses it in another
buffer: every time we do it, we have to be extra careful to make sure
the file name is absolute, and that's what the patch does.


        Stefan