One failed self test on Fedora 29

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?