Use old Cython build_ext until includes are fixed.

[robertwb]

This change in Cython 0.25

The distutils extension Cython.Distutils.build_ext has now been updated to use cythonize which properly handles dependencies. The old extension can still be found in Cython.Distutils.old_build_ext and is now deprecated.

seems to have broken the include of auto-generated algos_common_helper.pxi. As a temporary workaround, the old build_ext can be used.

[robertwb]

It looks like the difficulties are due to

1. The new Cython.Distutils.build_ext runs cythonize() in finalize_options(), before the .pxi files are generated, and
2. The extension objects use the include_dirs property, which is only inspected by the old build_ext.

[jreback]

well that will fail on older versions of cython wouldn't it?

need to check in a try except

further we use older (and newer versions) of cython in various builds

[robertwb]

Fixed.

[codecov-io]

Current coverage is 85.26% (diff: 100%)

Merging #14496 into master will decrease coverage by <.01%

@@             master     #14496   diff @@
==========================================
  Files           140        140          
  Lines         50667      50670     +3   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits          43203      43205     +2   
- Misses         7464       7465     +1   
  Partials          0          0          

Powered by Codecov. Last update d1d75d7...3d977c3

[jreback]

lgtm. can you add a release note, say compat with cython 0.25 builds.

was just about to say this isn't tested on travis, but cython JUST updated and broke our builds :>

[jreback]

so going to merge.

thanks!

[jreback]

I fixed the 3.4 build on the most recent cython. 6ac759d

If you would like to submit a PR to actually fix the way cython builds for >= 0.25 would be great! (need compat of course for older cythons). We still support >= 0.19.1, but should prob move that up.