Revert "Upgrade bazelbuild-rules_python to 0.28.0"

This reverts commit 1508c18d9e27325a8d9c574a90d205e0a1d8a78f.

Reason for revert: breaks build, not caught by treehugger

Change-Id: Id40b5eefc5f4f0f6e4a0122fbfa53b0c3c265985

1 files changed, 227 insertions, 0 deletions

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+<!-- Generated with Stardoc: http://skydoc.bazel.build -->
+
+Core rules for building Python projects.
+
+<a id="current_py_toolchain"></a>
+
+## current_py_toolchain
+
+<pre>
+current_py_toolchain(<a href="#current_py_toolchain-name">name</a>)
+</pre>
+
+
+    This rule exists so that the current python toolchain can be used in the `toolchains` attribute of
+    other rules, such as genrule. It allows exposing a python toolchain after toolchain resolution has
+    happened, to a rule which expects a concrete implementation of a toolchain, rather than a
+    toolchain_type which could be resolved to that toolchain.
+    
+
+**ATTRIBUTES**
+
+
+| Name  | Description | Type | Mandatory | Default |
+| :------------- | :------------- | :------------- | :------------- | :------------- |
+| <a id="current_py_toolchain-name"></a>name |  A unique name for this target.   | <a href="https://bazel.build/concepts/labels#target-names">Name</a> | required |  |
+
+
+<a id="py_import"></a>
+
+## py_import
+
+<pre>
+py_import(<a href="#py_import-name">name</a>, <a href="#py_import-deps">deps</a>, <a href="#py_import-srcs">srcs</a>)
+</pre>
+
+This rule allows the use of Python packages as dependencies.
+
+    It imports the given `.egg` file(s), which might be checked in source files,
+    fetched externally as with `http_file`, or produced as outputs of other rules.
+
+    It may be used like a `py_library`, in the `deps` of other Python rules.
+
+    This is similar to [java_import](https://docs.bazel.build/versions/master/be/java.html#java_import).
+    
+
+**ATTRIBUTES**
+
+
+| Name  | Description | Type | Mandatory | Default |
+| :------------- | :------------- | :------------- | :------------- | :------------- |
+| <a id="py_import-name"></a>name |  A unique name for this target.   | <a href="https://bazel.build/concepts/labels#target-names">Name</a> | required |  |
+| <a id="py_import-deps"></a>deps |  The list of other libraries to be linked in to the binary target.   | <a href="https://bazel.build/concepts/labels">List of labels</a> | optional | <code>[]</code> |
+| <a id="py_import-srcs"></a>srcs |  The list of Python package files provided to Python targets that depend on this target. Note that currently only the .egg format is accepted. For .whl files, try the whl_library rule. We accept contributions to extend py_import to handle .whl.   | <a href="https://bazel.build/concepts/labels">List of labels</a> | optional | <code>[]</code> |
+
+
+<a id="py_binary"></a>
+
+## py_binary
+
+<pre>
+py_binary(<a href="#py_binary-attrs">attrs</a>)
+</pre>
+
+See the Bazel core [py_binary](https://docs.bazel.build/versions/master/be/python.html#py_binary) documentation.
+
+**PARAMETERS**
+
+
+| Name  | Description | Default Value |
+| :------------- | :------------- | :------------- |
+| <a id="py_binary-attrs"></a>attrs |  Rule attributes   |  none |
+
+
+<a id="py_library"></a>
+
+## py_library
+
+<pre>
+py_library(<a href="#py_library-attrs">attrs</a>)
+</pre>
+
+See the Bazel core [py_library](https://docs.bazel.build/versions/master/be/python.html#py_library) documentation.
+
+**PARAMETERS**
+
+
+| Name  | Description | Default Value |
+| :------------- | :------------- | :------------- |
+| <a id="py_library-attrs"></a>attrs |  Rule attributes   |  none |
+
+
+<a id="py_runtime"></a>
+
+## py_runtime
+
+<pre>
+py_runtime(<a href="#py_runtime-attrs">attrs</a>)
+</pre>
+
+See the Bazel core [py_runtime](https://docs.bazel.build/versions/master/be/python.html#py_runtime) documentation.
+
+**PARAMETERS**
+
+
+| Name  | Description | Default Value |
+| :------------- | :------------- | :------------- |
+| <a id="py_runtime-attrs"></a>attrs |  Rule attributes   |  none |
+
+
+<a id="py_runtime_pair"></a>
+
+## py_runtime_pair
+
+<pre>
+py_runtime_pair(<a href="#py_runtime_pair-name">name</a>, <a href="#py_runtime_pair-py2_runtime">py2_runtime</a>, <a href="#py_runtime_pair-py3_runtime">py3_runtime</a>, <a href="#py_runtime_pair-attrs">attrs</a>)
+</pre>
+
+A toolchain rule for Python.
+
+This used to wrap up to two Python runtimes, one for Python 2 and one for Python 3.
+However, Python 2 is no longer supported, so it now only wraps a single Python 3
+runtime.
+
+Usually the wrapped runtimes are declared using the `py_runtime` rule, but any
+rule returning a `PyRuntimeInfo` provider may be used.
+
+This rule returns a `platform_common.ToolchainInfo` provider with the following
+schema:
+
+```python
+platform_common.ToolchainInfo(
+    py2_runtime = None,
+    py3_runtime = &lt;PyRuntimeInfo or None&gt;,
+)
+```
+
+Example usage:
+
+```python
+# In your BUILD file...
+
+load("@rules_python//python:defs.bzl", "py_runtime_pair")
+
+py_runtime(
+    name = "my_py3_runtime",
+    interpreter_path = "/system/python3",
+    python_version = "PY3",
+)
+
+py_runtime_pair(
+    name = "my_py_runtime_pair",
+    py3_runtime = ":my_py3_runtime",
+)
+
+toolchain(
+    name = "my_toolchain",
+    target_compatible_with = &lt;...&gt;,
+    toolchain = ":my_py_runtime_pair",
+    toolchain_type = "@rules_python//python:toolchain_type",
+)
+```
+
+```python
+# In your WORKSPACE...
+
+register_toolchains("//my_pkg:my_toolchain")
+```
+
+
+**PARAMETERS**
+
+
+| Name  | Description | Default Value |
+| :------------- | :------------- | :------------- |
+| <a id="py_runtime_pair-name"></a>name |  str, the name of the target   |  none |
+| <a id="py_runtime_pair-py2_runtime"></a>py2_runtime |  optional Label; must be unset or None; an error is raised otherwise.   |  <code>None</code> |
+| <a id="py_runtime_pair-py3_runtime"></a>py3_runtime |  Label; a target with <code>PyRuntimeInfo</code> for Python 3.   |  <code>None</code> |
+| <a id="py_runtime_pair-attrs"></a>attrs |  Extra attrs passed onto the native rule   |  none |
+
+
+<a id="py_test"></a>
+
+## py_test
+
+<pre>
+py_test(<a href="#py_test-attrs">attrs</a>)
+</pre>
+
+See the Bazel core [py_test](https://docs.bazel.build/versions/master/be/python.html#py_test) documentation.
+
+**PARAMETERS**
+
+
+| Name  | Description | Default Value |
+| :------------- | :------------- | :------------- |
+| <a id="py_test-attrs"></a>attrs |  Rule attributes   |  none |
+
+
+<a id="find_requirements"></a>
+
+## find_requirements
+
+<pre>
+find_requirements(<a href="#find_requirements-name">name</a>)
+</pre>
+
+The aspect definition. Can be invoked on the command line as
+
+    bazel build //pkg:my_py_binary_target         --aspects=@rules_python//python:defs.bzl%find_requirements         --output_groups=pyversioninfo
+
+
+**ASPECT ATTRIBUTES**
+
+
+| Name | Type |
+| :------------- | :------------- |
+| deps| String |
+
+
+**ATTRIBUTES**
+
+
+| Name  | Description | Type | Mandatory | Default |
+| :------------- | :------------- | :------------- | :------------- | :------------- |
+| <a id="find_requirements-name"></a>name |  A unique name for this target.   | <a href="https://bazel.build/concepts/labels#target-names">Name</a> | required |   |
+
+