tuple context not honored by extend tuple processor

[agentm]

The following tutd against the cjdate example db should be the equivalent of an outer join in SQL:

(relation{tuple{p# \"P7\", city \"Reykjavik\", color \"Beige\", pname \"Widget\", w\
eight 21}} union p : {suppliers := (sp rename {p# as pid} where p#=@pid) {s#}}) {p#,suppliers}

Due to a bug in the extend tuple processor, however, we get a type error instead. I discovered this bug in testing outer join equivalency.