Set GIT_ATTR_NOSYSTEM in test-lib to make tests more reliable in two
ways:
- an invalid GIT_ATTR_NOSYSTEM setting should not cause tests to fail
with "fatal: bad config value for 'GIT_ATTR_NOSYSTEM'".
- /etc/gitattributes should not change the outcome of tests.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Improved-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>