unnested_or_patterns trigger on master build even if feature is not enabled

[matthiaskrgr]

When using the master toolchain and a clippy built by master, the unnested_or_patterns lint triggers on crates although the or_patterns feature is not enabled in these crates.

This does not happen if the nightly-clippy is used.

See #5378 (comment) for details

[CAD97]

I just saw this lint with cargo +nightly-2020-06-16 clippy, so I think this is triggering in nightly-clippy as well now.

[repi]

Ran into this with nightly (clippy 0.0.212 (e55d3f9c5 2020-06-18)) now also, this clippy suggestions:

warning: unnested or-patterns
   --> component_accessors.rs:701:13
    |
701 | /             (D6Joint::RelativePosition, _)
702 | |             | (D6Joint::RelativeRotation, _)
703 | |             | (D6Joint::RelativeAngles, _) => {
    | |__________________________________________^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnested_or_patterns
help: nest the patterns
    |
701 |             (D6Joint::RelativePosition | D6Joint::RelativeRotation |
702 |  D6Joint::RelativeAngles, _) => {

But changing the code to this does indeed fail as it is an experimental feature we do not have enabled:

error[E0658]: or-patterns syntax is experimental
   --> components/component_accessors.rs:702:17
    |
702 |                 D6Joint::RelativePosition | D6Joint::RelativeRotation | D6Joint::RelativeAngles,
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: see issue #54883 <https://github.com/rust-lang/rust/issues/54883> for more information
    = help: add `#![feature(or_patterns)]` to the crate attributes to enable