Cargo lock on build directory does not work on NFS

When run on a project located on a NFS mount, cargo fails to lock the build directory.

Expected behavior:

# cd /tmp
# cargo new --bin bin
     Created binary (application) `bin` project
# cd bin
# cargo run & cargo run
    Blocking waiting for file lock on build directory
   Compiling bin v0.1.0 (file:///tmp/bin)
    Finished dev [unoptimized + debuginfo] target(s) in 0.57 secs
     Running `target/debug/bin`
Hello, world!
    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/bin`
Hello, world!

Actual behavior (my /home is NFSv4 mounted, with no lock-related options on the mount):

# cd $HOME/src
# cargo new --bin bin
     Created binary (application) `bin` project
# cd bin
# cargo run & cargo run
   Compiling bin v0.1.0 (file:///home/bruce/src/bin)
   Compiling bin v0.1.0 (file:///home/bruce/src/bin)
error: failed to remove /home/bruce/src/bin/target/debug/deps/bin-291ef6a9e055a048.0.o: No such file or directory (os error 2)

error: failed to remove /home/bruce/src/bin/target/debug/deps/bin-291ef6a9e055a048.crate.metadata.o: No such file or directory (os error 2)

error: failed to remove /home/bruce/src/bin/target/debug/deps/bin-291ef6a9e055a048.crate.allocator.o: No such file or directory (os error 2)

    Finished dev [unoptimized + debuginfo] target(s) in 0.90 secs
     Running `target/debug/bin`
    Finished dev [unoptimized + debuginfo] target(s) in 0.96 secs
     Running `target/debug/bin`
Hello, world!
Hello, world!

I'm using cargo 0.22.0 (3423351a5 2017-10-06) on Gentoo Linux, kernel 4.9.52.

Reproduce the failure by running two cargo run commands concurrently for a project on an NFS mount, comparing it with the /tmp example. Investigate Cargo's build-directory locking behavior and the reported missing object-file removals. Done means concurrent builds on NFS serialize correctly without the errors shown.