t0008: avoid absolute path

The colon is used by check-ignore to separate paths from other output
values. If we use an absolute path, however, on Windows it will be
converted into a Windows path that very much contains a colon.

It is actually not at all necessary to make the path of the global
excludes absolute, so let's just not even do that.

Based on suggestions by Karsten Blees and Junio Hamano.

Suggested-by: Karsten Blees <karsten.blees@gmail.com>
Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t0008-ignores.sh

@@ -5,7 +5,7 @@ test_description=check-ignore
 . ./test-lib.sh
 
 init_vars () {
-	global_excludes="$(pwd)/global-excludes"
+	global_excludes="global-excludes"
 }
 
 enable_global_excludes () {