51 MB seems excessive for CI storate and considering the nature of the test.
(note : maybe we should consider using `/tmp` for files generated during tests,
as tmpfs is typically using RAM, thus preserving storage.)
test -f tmp4
println "test : survive the list of files with too long filenames (--filelist=FILE)"
-datagen -g51M > tmp_badList
+datagen -g5M > tmp_badList
zstd -f --filelist=tmp_badList && die "should have failed : file name length is too long"
println "test : survive a list of files which is text garbage (--filelist=FILE)"