Toml@0.5.7 will sometimes fail to serialize

[johnsonw]

Toml@0.5.7 will sometimes fail and produce the following error with a structure that can
be converted into valid toml:

Result::unwrap() on an Err value: ValueAfterTable

The crate can correctly serialize such objects in version 0.8.1.

Example:

 #[derive(serde::Serialize)]
  pub struct MyObjectTest {
      pub obj: MyObject,
  }

  #[derive(serde::Serialize)]
  pub struct Boat {
      pub length: i32,
      pub has_motor: bool,
  }

  #[derive(serde::Serialize)]
  pub struct MyObject {
      pub name: String,
      pub boat: Option<Boat>,
      pub registered: bool,
  }

  let obj = MyObject {
      name: "Frosty".to_string(),
      boat: Some(Boat {
          length: 21,
          has_motor: true,
      }),
      registered: true,
  };

Serializing this struct with toml@0.5.7 will result in:

`Result::unwrap()` on an `Err` value: ValueAfterTable

After updating toml to 0.8.1, the same structure will serialize to:

name = "Frosty"
registered = true

[boat]
length = 21
has_motor = true

[ilyagr]

This might also be related to #439.

[mitsuhiko]

Closing this as a duplicate of #439