Problem with ALTER TABLE - occasional "tuple concurrently updated"

I have a process which runs in parallel creating tables which, as the
/final/ step in the import, gets SQL much like the following applied:

ALTER TABLE foo INHERIT bar;

Periodically, I get this error: tuple concurrently updated

Of course, I googled for the error message and see a bunch of issues
involving ANALYZE and even DROP function.
Is this the same root cause? Is there a fix? Is there a lock I could
take or some other approach that would prevent the error?
I thought all ALTER TABLE statements took a big fat lock to prevent
such an issue.

--
Jon