bug#5475: Archives with filenames with square brackets

[Eli Zaretskii]

> From: Juri Linkov <juri@jurta.org>
> Cc: Chong Yidong <cyd@stupidchicken.com>,  5475@debbugs.gnu.org
> Date: Sun, 31 Jan 2010 00:59:12 +0200
> 
> The default value of `archive-zip-extract' can be either "unzip" or
> "pkunzip" (depending on the presence of the executable in `exec-path'),
> but the function `archive-zip-extract' compares with the value "pkzip".
> So the pkzip/pkunzip branch is never executed.
> 
> It seems the intention of the change revno#45347 (2002-05-19) was
> to compare with "pkunzip" instead of "pkzip"

Right, looks like a bug.

Btw, I looked into 7z, and it doesn't have the same problem as unzip.
So we probably should only quote with unzip.