t5500: fix mistaken $SERVER reference in helper function

t5500: fix mistaken $SERVER reference in helper function

The end of t5500 contains two tests which use a single helper function,
fetch_filter_blob_limit_zero(). It takes a parameter to point to the
path of the server repository, which we store locally as $SERVER. The
first caller uses the relative path "server", while the second points
into the httpd document root.

Commit 07ef3c6604 (fetch test: use more robust test for filtered
objects, 2019-12-23) refactored some lines, but accidentally switched
"$SERVER" to "server" in one spot. That means the second caller is
looking at the server directory from the previous test rather than its
own.

This happens to work out because the "server" directory from the first
test is still hanging around, and the contents of the two are identical.
But it was clearly not the intended behavior, and is fragile to cleaning
up the leftovers from the first test.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>