https://bugzilla.redhat.com/show_bug.cgi?id=1008619

1,003 bytes in 1 blocks are definitely lost in loss record 599 of 635
==404== by 0x50728A7: virBufferAddChar (virbuffer.c:185)
==404== by 0x50BC466: virSystemdEscapeName (virsystemd.c:67)
==404== by 0x50BC6B2: virSystemdMakeSliceName (virsystemd.c:108)
==404== by 0x50BC870: virSystemdCreateMachine (virsystemd.c:169)
==404== by 0x5078267: virCgroupNewMachine (vircgroup.c:1498)