CI: invalidate cache when .pxi.in only changes

[jreback]

In the following, only the .pxi.in were changed and setup.py correctly has dependencies on these, so local building is fine. However, on travis, the cython cache does not seem to be invalidation (and I had to resort to manually clearing it).

similar to my comment: #14937 (comment)

happened again on merging: #15139, see: https://travis-ci.org/pandas-dev/pandas/jobs/193092807

[jreback]

any ideas

cc @gfyoung
@chris-b1

[chris-b1]

It's probably the same solution from #14363 (which was pxd) - adding pyx.in to those ci scripts.

[jreback]

ahh that makes sense.

[gfyoung]

I wonder if you could log the timestamps and see what Travis is getting on the files. We have the logic to update those files in the setup, but it's not firing.