Merge lp:~jelmer/brz/cython-version into lp:brz

[Jelmer Vernooij]

Don't use cython if it's too old.

Don't use cython if it's too old.

We currently require at least version 0.29, since older versions generate C code that doesn't build against Python 3.7.

=== modified file 'doc/en/user-guide/installing_breezy.txt'
--- doc/en/user-guide/installing_breezy.txt	2018-11-18 13:43:04 +0000
+++ doc/en/user-guide/installing_breezy.txt	2019-02-17 17:48:19 +0000
@@ -90,7 +90,7 @@
   3. Put the created directory on your PATH.
 
 Advanced users may also wish to build the optional C extensions for greater
-speed. This can be done using ``make`` and requires ``pyrex`` and a C compiler.
+speed. This can be done using ``make`` and requires ``cython`` and a C compiler.
 Please contact us on email or IRC if you need assistance with this.
 
 

=== modified file 'setup.py'
--- setup.py	2019-02-06 05:44:37 +0000
+++ setup.py	2019-02-17 17:48:19 +0000
@@ -211,8 +211,17 @@
     print("")
     from distutils.command.build_ext import build_ext
 else:
-    have_cython = True
+    minimum_cython_version = '0.29'
     cython_version_info = LooseVersion(cython_version)
+    if cython_version_info < LooseVersion(minimum_cython_version):
+        print("Version of Cython is too old. "
+              "Current is %s, need at least %s."
+              % (cython_version, minimum_cython_version))
+        print("If the .c files are available, they will be built,"
+              " but modifying the .pyx files will not rebuild them.")
+        have_cython = False
+    else:
+        have_cython = True
 
 
 class build_ext_if_possible(build_ext):