Dropping schemas and "illegal seek"

I have a perl test program which has about 80 test cases, each of
which creates its own schema so I can remove them with DROP SCHEMA xxx
CASCADE.  Normally each test case creates and drops the same schema,
but it can run a mode to preserve each schema and all the disk files
for each test.  I recently changed my cleanup code to run psql with
all -c commands on one command line rather than a separate psql -c for
each one ...

    psql -c 'DROP SCHEMA x1 CASCADE'
    psql -c 'DROP SCHEMA x2 CASCADE'
    ...

changed to

    psql -c 'DROP SCHEMA x1 CASCADE' -c 'DROP SCHEMA x2 CASCADE' ...

and began getting this complaint from psql:

    Can't drop schemas: Illegal seek

But nothing in the server log.  I have set log_min_messages = warning
and maybe that accounts for it, but illegal seek sounds bad enough to
be at least a warning.

I changed it back to separate commands, and the illegal seek complant
only shows up for the last one (which is dropped).  I tried adding
sleep 5 between each command, no difference.

VACUUM ANALYZE doesn't clear it.  I can recreate all 80 schema and
delete them all and get the same message.

Have I hosed this database?

--
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     Felix Finch: scarecrow repairman & rocket surgeon / felix@crowfix.com
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I've found a solution to Fermat's Last Theorem but I see I've run out of room o