Fixing captures (#723)

* WIP fixing captures

* small fix

* WIP

* Rewrite to proof-of-concept better parse_def

* Add missing file

* Finish capture refactor

* Fix tests

* Add more tests

crates/nu-protocol/src/ast/expression.rs

@@ -112,6 +112,10 @@ impl Expression {
             Expr::Block(block_id) => {
                 let block = working_set.get_block(*block_id);
 
+                if block.captures.contains(&IN_VARIABLE_ID) {
+                    return true;
+                }
+
                 if let Some(Statement::Pipeline(pipeline)) = block.stmts.get(0) {
                     match pipeline.expressions.get(0) {
                         Some(expr) => expr.has_in_variable(working_set),