Update posts/2021-02-11-Rust-1.50.0.md

Author: Mark-Simulacrum

posts/2021-02-11-Rust-1.50.0.md

@@ -86,7 +86,7 @@ constants, you can look forward to inline `const` expressions per [RFC 2920].
 Rust 1.49 made it possible to add `ManuallyDrop<T>` fields to a `union` as part
 of allowing `Drop` for unions at all. However, unions don't drop old values
 when a field is assigned, since they don't know which variant was formerly
-valid, so safe Rust has limited this to `Copy` types only, which never `Drop`.
+valid, so safe Rust previously limited this to `Copy` types only, which never `Drop`.
 Of course, `ManuallyDrop<T>` also doesn't need to `Drop`, so now Rust 1.50
 allows safe assignments to these fields as well.