Build failure with cython 0.28

[asitstands]

make cython, which runs python setup.py build_ext --inplace --with-cython, fails with the following errors. My environment is Arch linux with python 3.6.4, cython 0.28.1, and setuptools 39.0.1.

Compiling mxnet/cython/ndarray.pyx because it changed.
Compiling mxnet/cython/symbol.pyx because it changed.
[1/2] Cythonizing mxnet/cython/ndarray.pyx

Error compiling Cython file:
------------------------------------------------------------
...
# Licensed to the Apache Software Foundation (ASF) under one
^
------------------------------------------------------------

mxnet/cython/ndarray.pyx:1:0: 'mxnet/_cy3/.ndarray' is not a valid module name
Traceback (most recent call last):
  File "setup.py", line 108, in <module>
    ext_modules=config_cython(),
  File "setup.py", line 96, in config_cython
    return cythonize(ret)
  File "/usr/lib/python3.6/site-packages/Cython/Build/Dependencies.py", line 1026, in cythonize
    cythonize_one(*args)
  File "/usr/lib/python3.6/site-packages/Cython/Build/Dependencies.py", line 1146, in cythonize_one
    raise CompileError(None, pyx_file)
Cython.Compiler.Errors.CompileError: mxnet/cython/ndarray.pyx

Downgrading cython to 0.27.3 resolves this but gives warnings and different errors.

Warning: Extension name 'mxnet/_cy3/.ndarray' does not match fully qualified name 'ndarray' of 'mxnet/cython/ndarray.pyx'
Warning: Extension name 'mxnet/_cy3/.symbol' does not match fully qualified name 'symbol' of 'mxnet/cython/symbol.pyx'
Compiling mxnet/cython/ndarray.pyx because it changed.
Compiling mxnet/cython/symbol.pyx because it changed.
[1/2] Cythonizing mxnet/cython/ndarray.pyx
[2/2] Cythonizing mxnet/cython/symbol.pyx
running build_ext
error: each element of 'ext_modules' option must be an Extension instance or 2-tuple

If I run python setup.py build_ext --with-cython (without --inplace), the build succeeds with cython 0.27.3.

[anirudhacharya]

@nswamy @sandeep-krishnamurthy please label this - "Build"

[karan6181]

@mxnet-label-bot add [Bug]

[karan6181]

This issue is similar to #10738 and might be fixed by #10951.

[karan6181]

Duplicate of #10738

[karan6181]

@Roshrini Can you please mark this bug as a duplicate of #10738 and close it. Thank you!

[nswamy]

closing as duplicate

[karan6181]

@mxnet-label-bot add [python]