error message with poudriere

[FormerUSMCe5 at aim.com]

Running the devel/poudriere version of poudriere on a freebsd 11.2 amd64
machine, I am often presented with this message:

+swap_pager_getswapspace(18): failed

The number in parentheses changes, but the message stays the same. The
message is printed literally hundreds of times.

Exactly what does it mean, and what do I do to correct it? I cannot find
anything in the poudriere documentation that mentions it.

-- 
Sgt