default prefix not honored, gzip 1.3.13, possibly before?

[Zube]

A newly installed CentOS 5.3 x86_64 machine, with a mostly unpopulated
/usr/local.  gzip has never been installed under /usr/local, the
only gzip that exists is the local system one (/usr/bin/gzip, a link
to /bin/gzip).

I run:

./configure
gmake
gmake install

and it drops the install in /usr/bin.  Starting on line 19611 of the
configure script, the prefix is changed based on where gzip is
currently installed.  This is surprising and annoying behavior.
The configure script is explicit:

./configure --help

***

Installation directories:
  --prefix=PREFIX         install architecture-independent files in PREFIX
                          [/usr/local]

By default, `make install' will install all the files in
`/usr/local/bin', `/usr/local/lib' etc.

***

Thanks to this errant behavior (off the top of my head, I know of no
other GNU program that does this), I'm going to have a bit of manual
undo to do.  I can force the build to do what I want with: 

./configure --prefix=/usr/local

but dear me, I shouldn't have to.

Could you please either document this behavior and change the output of
./configure --help or remove the check completely?  It makes no sense
to change the default install location based on where gzip is found.

Cheers,
Zube