no support for duplicate keys

[clux]

it is not possible to pass stuff like:

foo:
  bar: 1
  bar: 2

through yq. you'll get: Error: foo: duplicate entry with key "bar" at line 2 column 3, which tbh is correct, and it's (i think) what serde_yaml enforces.

unfortunately... tools like helm allow you doing this, and there are some charts that rely on the second set of key overriding the first (taking precedence)... so leaving this issue here as a link from caveats.

EDIT: not even sure if the above helm use case works anymore; ci systems such as flux's kustomize-controller just flat out reject duplicate keys now

don't really want to support this because it is bad, and i don't even think this is practically possible with serde_yaml. probably wontfix.

[clux]

NB: jq does also support this type of awkward key precedence:

$ echo '{"foo": 1, "foo": 2}' > duplicate.json
$ jq .foo duplicate.json
2

[clux]

toml parser also chokes on this in rust:

Error: TOML parse error at line 8, column 1
  |
8 | version = "0.6.0"
  | ^
duplicate key `version` in table `package`

when inserting a duplicate key in Cargo.toml.

probably best to stay consistent and have this crate be strict about things.