[Cython] git master fails to compile scipy

[Julian Taylor]

hi,
since ab78f93b3ffa88183a0d2aae6b692e394c51f860 scipy does not build anymore:
the failing file is:
https://github.com/scipy/scipy/blob/master/scipy/sparse/csgraph/_reordering.pyx

error:
Traceback (most recent call last):
  File "/usr/bin/cython", line 8, in <module>
    main(command_line = 1)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Main.py",
line 704, in main
    result = compile(sources, options)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Main.py",
line 679, in compile
    return compile_multiple(source, options)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Main.py",
line 657, in compile_multiple
    result = run_pipeline(source, options, context=context)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Main.py",
line 487, in run_pipeline
    err, enddata = Pipeline.run_pipeline(pipeline, source)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Pipeline.py",
line 365, in run_pipeline
    data = phase(data)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Pipeline.py",
line 53, in generate_pyx_code_stage
    module_node.process_implementation(options, result)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/ModuleNode.py",
line 118, in process_implementation
    self.generate_c_code(env, options, result)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/ModuleNode.py",
line 349, in generate_c_code
    self.body.generate_function_definitions(env, code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 436, in generate_function_definitions
    stat.generate_function_definitions(env, code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 436, in generate_function_definitions
    stat.generate_function_definitions(env, code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/FusedNode.py",
line 785, in generate_function_definitions
    stat.generate_function_definitions(env, code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 3068, in generate_function_definitions
    FuncDefNode.generate_function_definitions(self, env, code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 1935, in generate_function_definitions
    self.generate_function_body(env, code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 1691, in generate_function_body
    self.body.generate_execution_code(code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 442, in generate_execution_code
    stat.generate_execution_code(code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/UtilNodes.py",
line 321, in generate_execution_code
    self.body.generate_execution_code(code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 6419, in generate_execution_code
    self.body.generate_execution_code(code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 442, in generate_execution_code
    stat.generate_execution_code(code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 5865, in generate_execution_code
    if_clause.generate_execution_code(code, end_label, is_last=i == last)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 5908, in generate_execution_code
    self.body.generate_execution_code(code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 442, in generate_execution_code
    stat.generate_execution_code(code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 4800, in generate_execution_code
    self.generate_assignment_code(code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/Nodes.py",
line 5091, in generate_assignment_code
    self.lhs.generate_assignment_code(self.rhs, code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/ExprNodes.py",
line 3897, in generate_assignment_code
    self.generate_buffer_setitem_code(rhs, code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/ExprNodes.py",
line 3905, in generate_buffer_setitem_code
    buffer_entry, ptrexpr = self.buffer_lookup_code(code)
  File
"/tmp/local/lib/python2.7/site-packages/Cython-0.24.0a0-py2.7-linux-x86_64.egg/Cython/Compiler/ExprNodes.py",
line 3873, in buffer_lookup_code
    for ivar in self.indices]
AttributeError: 'NoneType' object has no attribute 'signed'