Error::cause is deprecated in Rust 1.33

[taiki-e]

Version

• tokio v0.1.13
• tokio-timer v0.2.8

Subcrates

• tokio-timer

Description

Error::cause is deprecated in Rust 1.33, but Error::source, which replaces it, has been stabilized in Rust 1.30 (the minimum version of tokio is Rust 1.26).

This is the cause of the build error in current nightly.

Related: rust-lang/rfcs#2504, rust-lang/rust#53533