unexpected EOF on client connection with an open transaction

[qwfy]

When compiling a .ml containing let f dbh k = PGSQL(dbh) "select a from foo where k = $k, and you open pg's log file, you would see something like this:

LOG:  execute nullable: select attnotnull from pg_attribute where attrelid = $1 and attnum = $2
DETAIL:  parameters: $1 = '17195', $2 = '7'
LOG:  unexpected EOF on client connection with an open transaction

When actually running the query, i.e., when later you do a f dbh some_key, there is no such message.

Is this intentional or a bug?