converters/py-rencode: Fails to configure if cython is installed

ports r482774 removed USE_PYTHON=cython, likely due to it (cython) not
being explicitly declared as a dependency in setup.py:*_requires.

However, setup.py conditionally builds with cython if it is installed, but
the 1.0.6 source distribution (sdist) does not contain a .pyx file to build
with.

This leads to a configure/build error when cython is installed:

  ValueError: 'rencode/rencode.pyx' doesn't match any files

Upstream commit 5c928f14567fabc9efb8bbb8ac5e0eef03c61541 [1] via issue
#25 [2] adds the required .pyx file to the sdist, which technically
addresses the "build with cython from the sdist" issue, but does not
fundamentally resolve the higher-level question: why build with cython when
a C source pre-processed by cython has already been produced for, and is
contained in, the source distribution.

A cython build (and the dependency on cython) does not appear to be
necessary, nor intended [3][4], nor recommended [5], even after #25 is
released, for sdist consumers.

The conditional code to build with cython should not be included in
setup.py, at least not as a default case, or without an explicit request
by the user to use cython, as an optional build method, for sdist consumers
(most downstream packagers and setuptools/pip users [6]).

This change removes the conditional check for Cython, leaving the standard
setuptools build_ext (with the packaged .c) file, as the build method.

While I'm here:

 - Canonicalise COMMENT (match seutp.py:description)
 - Add test target with post-patch target to make the tests dir a module
   usable by a setup.py test (via test_suite directive) target.
 - Honour CFLAGS: Remove forced (appended) -O3 arg from setup.py

[1] https://github.com/aresch/rencode/commit/5c928f14567fabc9efb8bbb8ac5e0eef03c61541
[2] https://github.com/aresch/rencode/pull/25
[3] setup.py: "Error: sdist requires cython module to generate `.c` file."
[4] dev-requirements.txt:Cython
[5] https://cython.readthedocs.io/en/latest/src/userguide/source_files_and_compilation.html#distributing-cython-modules
[6] https://github.com/aresch/rencode/issues/11

PR:		233561
Reported by:	John Hein <z7dr6ut7gs snkmail com>
Approved by:	koobs (python)

1 files changed, 35 insertions, 0 deletions

diff --git a/converters/py-rencode/files/patch-setup.py b/converters/py-rencode/files/patch-setup.py
new file mode 100644
index 000000000000..8c34a7b2e316
--- /dev/null
+++ b/converters/py-rencode/files/patch-setup.py
@@ -0,0 +1,35 @@
+# 1) converters/py-rencode: Fails to configure if cython is installed
+# 2) make setup.py test command work via test_suite directive
+# 3) Honour/respect user CFLAGS
+# https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=233561
+
+--- setup.py.orig	2018-10-21 17:41:35 UTC
++++ setup.py
+@@ -29,19 +29,14 @@ from distutils.errors import CCompilerError, Distutils
+ from setuptools import setup
+ from setuptools.extension import Extension
+ 
+-try:
+-    from Cython.Build import build_ext
+-    from Cython.Build import cythonize
+-except ImportError as ex:
+-    from setuptools.command.build_ext import build_ext
+-    cythonize = False
++from setuptools.command.build_ext import build_ext
++cythonize = False
+ 
+ source_ext = ".pyx" if cythonize else ".c"
+ 
+ ext_modules = [
+     Extension(
+         "rencode._rencode",
+-        extra_compile_args=["-O3"],
+         sources=["rencode/rencode" + source_ext],
+     ),
+ ]
+@@ -93,4 +88,5 @@ setup(
+   cmdclass={'build_ext': optional_build_ext},
+   ext_modules=ext_modules,
+   setup_requires=['setuptools', 'wheel'],
++  test_suite='tests',
+ )