Enable cython caching

[robertwb]

The entire Sage library fits into about 25MB (compressed) cache.

Component: build

Author: Robert Bradshaw

Branch/Commit: u/vbraun/ticket/15430 @ 064791b

Reviewer: Volker Braun

Issue created by migration from https://trac.sagemath.org/ticket/15430

[robertwb]

Branch: u/robertwb/ticket/15430

[robertwb]

Author: Robert Bradshaw

[robertwb]

New commits:

[c93d084](https://github.com/sagemath/sagetrac-mirror/commit/c93d084)

Enable cython cache.

[robertwb]

Commit: c93d084

[robertwb]

Description changed:

--- 
+++ 
@@ -1 +1 @@
-
+The entire Sage library fits into about 25MB (compressed) cache. 

[vbraun]

Reviewer: Volker Braun

[vbraun]

comment:3

Dependency checking seems to work for me. If there is any problem left then I'm pretty sure we'll only be able to find it if we use this seriously. So I'm in favor of pushing this into the sage-git release....

[vbraun]

comment:4

Building Sage with a non-existing DOT_SAGE breaks because of this ticket. From the buildbot:

Compiling sage/ext/interpreters/wrapper_rdf.pyx because it changed.
Compiling sage/ext/interpreters/wrapper_cdf.pyx because it changed.
Compiling sage/ext/interpreters/wrapper_rr.pyx because it changed.
Compiling sage/ext/interpreters/wrapper_py.pyx because it changed.
Compiling sage/ext/interpreters/wrapper_el.pyx because it changed.
Traceback (most recent call last):
  File "setup.py", line 531, in <module>
    force=force)
  File "/home/buildbot/build/sage/plantain/sage_git/build/local/lib/python2.7/site-packages/Cython/Build/Dependencies.py", line 740, in cythonize
    os.mkdir(options.cache)
OSError: [Errno 2] No such file or directory: '/home/buildbot/build/sage/plantain/sage_git/dot_sage/cycache'