Coverity now started warning about this ("Calling unlinkat without checking
return value (as is done elsewhere 12 out of 15 times).", and it is right:
most of the time we should at list print a log message so people can figure
out something is wrong when this happens.
v2:
- use warning level in journald too (this is unlikely to happen ever, so it
should be safe to something that is visible by default).