One failed self test on Fedora 29

[Jeffrey Walton <noloader@gmail.com>]

Fedora 29, x86_64. One failed self test:

*** t0021-conversion.sh ***
ok 1 - setup
ok 2 - check
ok 3 - expanded_in_repo
ok 4 - filter shell-escaped filenames
ok 5 - required filter should filter data
ok 6 - required filter smudge failure
ok 7 - required filter clean failure
ok 8 - filtering large input to small output should use little memory
ok 9 - filter that does not read is fine
ok 10 # skip filter large file (missing EXPENSIVE)
ok 11 - filter: clean empty file
ok 12 - filter: smudge empty file
not ok 13 - disable filter with empty override
#
#               test_config_global filter.disable.smudge false &&
#               test_config_global filter.disable.clean false &&
#               test_config filter.disable.smudge false &&
#               test_config filter.disable.clean false &&
#
#               echo "*.disable filter=disable" >.gitattributes &&
#
#               echo test >test.disable &&
#               git -c filter.disable.clean= add test.disable 2>err &&
#               test_must_be_empty err &&
#               rm -f test.disable &&
#               git -c filter.disable.smudge= checkout -- test.disable 2>err &&
#               test_must_be_empty err
#
ok 14 - diff does not reuse worktree files that need cleaning
ok 15 - required process filter should filter data
ok 16 - required process filter takes precedence
ok 17 - required process filter should be used only for "clean" operation only
ok 18 - required process filter should process multiple packets
ok 19 - required process filter with clean error should fail
ok 20 - process filter should restart after unexpected write failure
ok 21 - process filter should not be restarted if it signals an error
ok 22 - process filter abort stops processing of all further files
ok 23 - invalid process filter must fail (and not hang!)
ok 24 - delayed checkout in process filter
ok 25 - missing file in delayed checkout
ok 26 - invalid file in delayed checkout
# failed 1 among 26 test(s)
1..26
gmake[2]: *** [Makefile:56: t0021-conversion.sh] Error 1

Does anyone need a config.log or other test data?