Spurious "no space left on device" exceptions

[alexcrichton]

Causing our builds to fail.

I have no idea why ;_;

[alexcrichton]

According to https://travis-ci.org/rust-lang/rust/jobs/209124004:

• We have 30GB of disk space 23 of which is available on the start of a build:

  Filesystem      Size  Used Avail Use% Mounted on
  none             30G  5.7G   23G  20% /
  

• At the end of the build, the obj/build dir is 23 GB:

  $ du -sbh obj/*
  23G	obj/build
  

And such, we're filling up.

[alexcrichton]

cc #40371

[alexcrichton]

According to https://travis-ci.org/rust-lang/rust/jobs/209140948 we start out with 5/30GB taken up

[alexcrichton]

Word from travis is that we can't increase disk size right now.

[alexcrichton]

According to https://s3.amazonaws.com/archive.travis-ci.org/jobs/209178163/log.txt the run-pass output directory is 17GB

[alexcrichton]

"Hello world" for musl is 3.5 MB. With 2.8k tests and three separate targets being tested, that's ~30GB. That's where the space is going.

[alexcrichton]

3.1MB of that 3.5 is debuginfo