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[jdetychey]

Fix for Cargo fail when building from source

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[jdetychey]

Build from source with:

$ cargo build --release

Can lead to this error:

failed to parse manifest at `~/parity/Cargo.toml`
Caused by:
  could not parse input as TOML
Cargo.toml:58:9 expected a key but found an empty string
Cargo.toml:58:9-58:10 expected `.`, but found `'`

The one line installer of rust leads to multiple version of cargo.:

$ curl https://sh.rustup.rs -sSf | sh

Notably:

cargo --version
cargo 0.8.0 (built 2016-03-22)

and:

$ ~/.cargo/bin/cargo build --version
cargo 0.16.0-nightly (6e0c18c 2017-01-27)

Therefore using instead:

~/.cargo/bin/cargo build --release

Fix it