crocket skribis: > 5. '/' includes '/tmp'. '/' is a btrfs. The mount options are > rw,noatime,compress=lzo,ssd,discard,space_cache,autodefrag OK, this seems to be the culprit, see: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=20570 As a workaround, using substitutes is indeed the best solution. I’m closing the bug. Thanks, Ludo’.