xargo 0.3.11 fails with older toolchains that don't have a bin subdirectory

[jcsoo]

xargo 0.3.11 with older toolchains (nightly-2017-12-23 as an example) produces this error on OSX:

xargo build -v --target thumbv7em-none-eabihf
+ "rustc" "--print" "sysroot"
+ "rustc" "--print" "target-list"
error: intermittent IO error while iterating directory `/Users/fsoo/.rustup/toolchains/nightly-2017-12-23-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/bin`
caused by: IO error for operation on /Users/fsoo/.rustup/toolchains/nightly-2017-12-23-x86_64-apple-darwin/lib/rustlib/x86_64-apple-darwin/bin: No such file or directory (os error 2)
caused by: No such file or directory (os error 2)
note: run with `RUST_BACKTRACE=1` for a backtrace

It appears this this is caused by db0191b7643c5b0599256a532e3d50b03a394f89, which doesn't check that the bin directory exists before attempting to copy it.

Workaround is to use 0.3.10.

Not sure if this is worth a version bump to fix, but posting this to make the issue and workaround more findable.

[leshow]

I was bitten by this error and have been unable to cross compile a project for a few weeks until I found this issue, thanks for saying something