Conform to protobuf's usage of six

bazel/grpc_python_deps.bzl

@@ -4,18 +4,12 @@ load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 load("@com_github_grpc_grpc//third_party/py:python_configure.bzl", "python_configure")
 
 def grpc_python_deps():
-    native.bind(
-        name = "six",
-        actual = "@six_archive//:six",
-    )
-
     # protobuf binds to the name "six", so we can't use it here.
     # See https://github.com/bazelbuild/bazel/issues/1952 for why bind is
     # horrible.
-    if "six_archive" not in native.existing_rules():
+    if "six" not in native.existing_rules():
         http_archive(
-            name = "six_archive",
-            strip_prefix = "six-1.12.0",
+            name = "six",
             build_file = "@com_github_grpc_grpc//third_party:six.BUILD",
             sha256 = "d16a0141ec1a18405cd4ce8b4613101da75da0e9a7aec5bdd4fa804d0e0eba73",
             urls = ["https://files.pythonhosted.org/packages/dd/bf/4138e7bfb757de47d1f4b6994648ec67a51efe58fa907c1e11e350cddfca/six-1.12.0.tar.gz"],

examples/python/cancellation/BUILD.bazel

@@ -43,7 +43,7 @@ py_binary(
     deps = [
         ":hash_name_py_pb2",
         ":hash_name_py_pb2_grpc",
-        "//external:six",
+        "@six//:six",
         "//src/python/grpcio/grpc:grpcio",
     ],
 )

src/python/grpcio/grpc/BUILD.bazel

@@ -18,7 +18,7 @@ py_library(
         "//src/python/grpcio/grpc/_cython:cygrpc",
         "//src/python/grpcio/grpc/experimental",
         "//src/python/grpcio/grpc/framework",
-        "@six_archive//:six",
+        "@six//:six",
     ] + select({
         "//conditions:default": ["@enum34//:enum34"],
         "//:python3": [],

src/python/grpcio/grpc/framework/foundation/BUILD.bazel

@@ -22,7 +22,7 @@ py_library(
     name = "callable_util",
     srcs = ["callable_util.py"],
     deps = [
-        "//external:six",
+        "@six//:six",
     ] + select({
         "//conditions:default": ["@enum34//:enum34"],
         "//:python3": [],
@@ -33,7 +33,7 @@ py_library(
     name = "future",
     srcs = ["future.py"],
     deps = [
-        "//external:six",
+        "@six//:six",
     ],
 )
 
@@ -58,6 +58,6 @@ py_library(
     name = "stream",
     srcs = ["stream.py"],
     deps = [
-        "//external:six",
+        "@six//:six",
     ],
 )

src/python/grpcio/grpc/framework/interfaces/base/BUILD.bazel

@@ -14,7 +14,7 @@ py_library(
     srcs = ["base.py"],
     deps = [
         "//src/python/grpcio/grpc/framework/foundation:abandonment",
-        "//external:six",
+        "@six//:six",
     ] + select({
         "//conditions:default": ["@enum34//:enum34"],
         "//:python3": [],

src/python/grpcio/grpc/framework/interfaces/face/BUILD.bazel

@@ -15,7 +15,7 @@ py_library(
     deps = [
         "//src/python/grpcio/grpc/framework/foundation",
         "//src/python/grpcio/grpc/framework/common",
-        "//external:six",
+        "@six//:six",
     ] + select({
         "//conditions:default": ["@enum34//:enum34"],
         "//:python3": [],

src/python/grpcio_tests/tests/unit/BUILD.bazel

@@ -102,7 +102,7 @@ py_library(
             ":resources",
             ":test_common",
             ":thread_pool",
-            "//external:six",
+            "@six//:six",
             "//src/python/grpcio/grpc:grpcio",
             "//src/python/grpcio_tests/tests/testing",
             "//src/python/grpcio_tests/tests/unit/framework/common",

src/python/grpcio_tests/tests_aio/benchmark/BUILD.bazel

@@ -22,7 +22,7 @@ py_binary(
     srcs = ["server.py"],
     python_version = "PY3",
     deps = [
-        "//external:six",
+        "@six//:six",
         "//src/proto/grpc/testing:benchmark_service_py_pb2",
         "//src/proto/grpc/testing:benchmark_service_py_pb2_grpc",
         "//src/proto/grpc/testing:py_messages_proto",

src/python/grpcio_tests/tests_aio/unit/BUILD.bazel

@@ -58,7 +58,7 @@ py_library(
             ":_constants",
             ":_test_base",
             ":_test_server",
-            "//external:six",
+            "@six//:six",
             "//src/proto/grpc/testing:benchmark_service_py_pb2",
             "//src/proto/grpc/testing:benchmark_service_py_pb2_grpc",
             "//src/proto/grpc/testing:py_messages_proto",

third_party/six.BUILD

@@ -1,6 +1,14 @@
+genrule(
+    name = "copy_six",
+    srcs = ["six-1.12.0/six.py"],
+    outs = ["__init__.py"],
+    cmd = "cp $< $(@)",
+)
+
 py_library(
     name = "six",
-    srcs = ["six.py"],
+    srcs = ["__init__.py"],
     srcs_version = "PY2AND3",
     visibility = ["//visibility:public"],
 )
+