Gzip testsuite uses system-installed gzip?

[Chris Staub]

I was looking at the gzip testsuite (gzip 1.3.12) and it uses the 
currently-installed gzip program to compress a file, then uses zdiff on 
the file. Considering that it seems odd to use a system-installed 
program for testing, I was wondering whether this was really 
intentional. If it is, it should at least be documented somewhere 
(comment by that command in the Makefile maybe).