In Linux Port, make a dummy HOME directory for running tests.

I haven't really confirmed that this solves the problem because I wasn't able to reproduce it again :-/

Note, there's a related change http://crrev.com/2143123004 which would make it so that the real os.environ isn't used in tests.

BUG=612730

Review-Url: https://codereview.chromium.org/2141093006
Cr-Commit-Position: refs/heads/master@{#405576}
2 files changed