Compile TensorFlow from source with gcc6.1

Due to two bugs in gcc 6.1 affecting the re2 library (one of which has been fixed in 6.2)), TensorFlow cannot be compiled from source one some systems (including my Debian Testing install).

To work around the issue, modify tensorflow/workspace.bzl and change the re2 description to:

  name = "com_googlesource_code_re2",
  remote = "",
  commit = "86503cb89d82b723ae0bce35e1e09524910cd319",

The re2 library is now downloaded from my fork, which applies a one line patch.

Compile the TensorFlow Python package as usual with:

bazel build -c opt //tensorflow/tools/pip_package:build_pip_package
bazel-bin/tensorflow/tools/pip_package/build_pip_package /tmp/tensorflow_pkg

After installing the pip wheel using

pip install /tmp/tensorflow_pkg/*.whl

you should have a working installation. If importing fails with

ImportError: cannot import name 'pywrap_tensorflow'

switch out of the TensorFlow source directory and try again.