Problem 1: main.loaddata tried to trigger an error caused by
reading files outside the vardir, by reading itself. However,
if loaddata.test is not world-readable (e.g., umask=0077),
then another error is triggered.
Fix 1: allow the other error too.
Problem 2: rpl_slave_skip and rpl_innodb_mixed_dml tried to
copy a file from mysql-test/suite/rpl/data to mysql-test/var
and then read it. That failed too if umask=0077, since the
file would not become world-readable.
Fix 2: move the files from mysql-test/suite/rpl/data to
mysql-test/std_data and update tests accordingly. Remove
the directory mysql-test/suite/rpl/data.