Auto merge of #446 - kamalmarhubi:bind-mount-in-ci, r=posborne
Auto merge of #446 - kamalmarhubi:bind-mount-in-ci, r=posborne

mount: Run test_mount_bind in CI

Looks like Travis allows bind mounts in their container infra now.

MarkusJais/nix-rust,geofft/nix-rust,xd009642/nix,MarkusJais/nix-rust,berkowski/nix,kamalmarhubi/nix-rust,carllerche/nix-rust,geofft/nix-rust,berkowski/nix,xd009642/nix,carllerche/nix-rust,kamalmarhubi/nix-rust,posborne/rust-nix,xd009642/nix,Susurrus/nix,asomers/nix,posborne/rust-nix,nix-rust/nix,Susurrus/nix,MarkusJais/nix-rust,kamalmarhubi/nix-rust,carllerche/nix-rust,nix-rust/nix,Susurrus/nix,posborne/rust-nix,asomers/nix,berkowski/nix,geofft/nix-rust