Cargo build hangs on "Blocking waiting for file lock on the registry index" after building Parity

Hi everyone! I'm new to Rust and trying to build Parity (Ethereum client) from source. After I run `cargo build`, the process reaches dependency downloading and then hangs with the message: ``` Blocking waiting for file lock on the registry index ``` I tried: 1. Deleting `~/.cargo/registry/cache/` and `~/.cargo/registry/index/` 2. Rebooting the computer 3. Running `cargo clean` Nothing helps. The cargo process hangs indefinitely, and I can't even interrupt it with Ctrl+C, I have to kill the process with `kill -9`. System: Ubuntu 20.04, Rust installed via rustup, latest stable version. Here's my Cargo.toml (simplified): ```toml [package] name = "parity" version = "1.0.0" edition = "2018" [dependencies] parity-ethereum = { git = "https://g