Detected by ASan in test_hsmtool_generatehsm:
==58698==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 120 byte(s) in 1 object(s) allocated from:
#0 0x4e6247 in malloc
#1 0x7f078452d672 in getdelim
SUMMARY: AddressSanitizer: 120 byte(s) leaked in 1 allocation(s).