Add bdist_ext functionality to versioneer. Resolves #17

Author: Pan

setup.py

@@ -12,7 +12,6 @@
 cpython = platform.python_implementation() == 'CPython'
 
 try:
-    from Cython.Build import cythonize
     from Cython.Distutils.extension import Extension
     from Cython.Distutils import build_ext
 except ImportError:

versioneer.py

@@ -1,5 +1,5 @@
 
-# Version: 0.18
+# Version: 0.18-1
 
 """The Versioneer - like a rocketeer, but for versions.
 
@@ -1559,6 +1559,25 @@ def run(self):
                 write_to_version_file(target_versionfile, versions)
     cmds["build_py"] = cmd_build_py
 
+    if "setuptools" in sys.modules:
+        from setuptools.command.build_ext import build_ext as _build_ext
+    else:
+        from distutils.command.build_ext import build_ext as _build_ext
+
+    class cmd_build_ext(_build_ext):
+        def run(self):
+            root = get_root()
+            cfg = get_config_from_root(root)
+            versions = get_versions()
+            _build_ext.run(self)
+            # now locate _version.py in the new build/ directory and replace
+            # it with an updated value
+            target_versionfile = os.path.join(self.build_lib,
+                                              cfg.versionfile_source)
+            print("UPDATING %s" % target_versionfile)
+            write_to_version_file(target_versionfile, versions)
+    cmds["build_ext"] = cmd_build_ext
+
     if "cx_Freeze" in sys.modules:  # cx_freeze enabled?
         from cx_Freeze.dist import build_exe as _build_exe
         # nczeczulin reports that py2exe won't like the pep440-style string