test-lib.sh: unset XDG_CONFIG_HOME

Now that git respects XDG_CONFIG_HOME for some lookups, we
must be sure to cleanse the test environment. Otherwise, the
user's XDG_CONFIG_HOME could influence the test results.

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: peff

t/test-lib.sh

@@ -61,6 +61,7 @@ unset VISUAL EMAIL LANGUAGE COLUMNS $(perl -e '
 	my @vars = grep(/^GIT_/ && !/^GIT_($ok)/o, @env);
 	print join("\n", @vars);
 ')
+unset XDG_CONFIG_HOME
 [email protected]
 GIT_AUTHOR_NAME='A U Thor'
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