Problem getting @@identity

Hello all,

I have a problem with getting @@identity from git master. The result is
always NULL. I have no idea what the underlying cause is, but the error
manifests at info.c line 2235:

col_stmt->internal = TRUE;
result = PGAPI_ExecDirect(hcol_stmt, (SQLCHAR *) columns_query,
SQL_NTS, 0);
if (!SQL_SUCCEEDED(result))
{
SC_full_error_copy(stmt, col_stmt, FALSE);
goto cleanup;
}

The ExecDirect() call fails with "Connection is already in use."
According to git bisect, the responsible commit is e85fbb "Use libpq for
everything", but I'm not totally certain because I had to skip a lot.

As for finding the actual problem and fixing it, I'm afraid I won't be
much help; the innards of this driver are a mystery to me.

--
Christian