Following the instructions for "setup_lab_tools", I see the failure
below during `build_externals`.  There's something wrong with the
"functools_lru_cache" package when we try to install it.

Aside from making developers' lives difficult, it's possible that this
breaks updates for push to prod.  So, this needs relatively urgent attention.

16:36:26 INFO | lrucache isn't present. Will install.
16:36:26 INFO | Fetching http://commondatastorage.googleapis.com/chromeos-mirror/gentoo/distfiles/backports.functools_lru_cache-1.4.tar.gz
16:36:27 INFO | Good checksum.
Traceback (most recent call last):
  File "src/third_party/autotest/files/utils/build_externals.py", line 194, in <module>
    sys.exit(main())
  File "src/third_party/autotest/files/utils/build_externals.py", line 79, in main
    package_dir, install_dir, set(options.names_to_check))
  File "src/third_party/autotest/files/utils/build_externals.py", line 145, in fetch_necessary_packages
    if not package.is_needed(install_dir):
  File "/usr/local/google/home/jrbarnette/repos/cros.tools-test/src/third_party/autotest/files/utils/external_packages.py", line 167, in is_needed
    if (not module.__file__.startswith(install_dir) and
AttributeError: 'module' object has no attribute '__file__'
A late step in this process emits a number of Python SyntaxErrors.
The installation has most likely succeeded.
Consult http://sites/chromeos/for-team-members/infrastructure/lab-tools
for sample output from a successful run.