message: Clean up join.rs code, remove "&columns" which is not necessary
diff: @@ -100,10 +100,10 @@ impl<'a, T: 'static + Debug> Join<'a, T> {
  .next()
  .transpose()?;
  - Ok(match row {
  + let row = match row {
  Some((columns, key, row)) => Some(BlendContext {
  table,
  - columns: &columns,
  + columns,
  key,
  row,
  next: blend_context.map(|c| Box::new(c)),
  @@ -115,6 +115,8 @@ impl<'a, T: 'static + Debug> Join<'a, T> {
  return Err(JoinError::JoinTypeNotSupported.into());
  }
  },
  - })
  + };
  +
  + Ok(row)
  }
  }
  