[bfss] Catch EnvironmentError instead of OSError when trying to read attributes bffstored
This will also catch IOError (as file not found) that might be encountered expectable too.
ifnotrql('CWConstraintType X WHERE X name "RQLUniqueConstraint"',ask_confirm=False):rql('INSERT CWConstraintType X: X name "RQLUniqueConstraint"',ask_confirm=False)