Can't infer unique symbol types via another variable

Literals such as 0 can be inferred correctly but unique symbols are not.

TypeScript Version: 3.7.x-dev.20191224

Search Terms:

Code

let revision: symbol;
const rev = revision = Symbol();
rev === revision;

Expected behavior:
Type rev is unique symbol.
Actual behavior:
Type rev is symbol. Can't even declare that rev is a unique symbol.
Playground Link: https://www.typescriptlang.org/play/index.html?ts=3.8.0-dev.20191224&ssl=1&ssc=1&pln=3&pc=18#code/DYUwLgBATiBuCWBneB7AdgLgogngWwCMVgBuAKAGN1FIZYIBeaOJVNRiAZXyOAAoAlOTqMGTOq3QkgA

Related Issues:

首先，使用报告中的 3.8.0-dev 版本在链接的 TypeScript Playground 中复现示例，然后比较字面量示例的推断结果与 unique symbol 赋值的推断结果。issue 中没有指定源文件或测试；完成标准是，在所提供的代码中，rev 被推断为 unique symbol 而不是 symbol。