message: Support Python 3 in Poplar tests
  Summary:
  Note the documentation for Bazel says `srcs_version` is for documentation only and has no effect on which versoin of Python is run, but that appears to be nonsense.
  Fixes T1939
  Test Plan: Tests pass now.
  Reviewers: davidn
  Maniphest Tasks: T1939
diff: @@ -209,6 +209,7 @@ py_test(
  deps = [
  "//tensorflow:tensorflow_py",
  ],
  + srcs_version = "PY2AND3",
  )
  py_test(
  @@ -218,6 +219,7 @@ py_test(
  deps = [
  "//tensorflow:tensorflow_py",
  ],
  + srcs_version = "PY2AND3",
  )
  py_test(
  @@ -227,6 +229,7 @@ py_test(
  deps = [
  "//tensorflow:tensorflow_py",
  ],
  + srcs_version = "PY2AND3",
  )
  py_test(
  @@ -236,6 +239,7 @@ py_test(
  deps = [
  "//tensorflow:tensorflow_py",
  ],
  + srcs_version = "PY2AND3",
  )
  py_test(
  @@ -245,6 +249,7 @@ py_test(
  deps = [
  "//tensorflow:tensorflow_py",
  ],
  + srcs_version = "PY2AND3",
  )
  py_test(
  @@ -254,6 +259,7 @@ py_test(
  deps = [
  "//tensorflow:tensorflow_py",
  ],
  + srcs_version = "PY2AND3",
  )
  py_test(
  @@ -263,6 +269,7 @@ py_test(
  deps = [
  "//tensorflow:tensorflow_py",
  ],
  + srcs_version = "PY2AND3",
  )
  py_test(
  @@ -272,6 +279,7 @@ py_test(
  deps = [
  "//tensorflow:tensorflow_py",
  ],
  + srcs_version = "PY2AND3",
  )
  py_test(
  @@ -281,6 +289,7 @@ py_test(
  deps = [
  "//tensorflow:tensorflow_py",
  ],
  + srcs_version = "PY2AND3",
  )
  py_test(
  @@ -290,6 +299,7 @@ py_test(
  deps = [
  "//tensorflow:tensorflow_py",
  ],
  + srcs_version = "PY2AND3",
  )
  py_test(
  @@ -299,6 +309,7 @@ py_test(
  deps = [
  "//tensorflow:tensorflow_py",
  ],
  + srcs_version = "PY2AND3",
  )
  test_suite(
  