avoid pbr's non multi-version aware script

otherwise the latest ryu-manager can pick up older modules
if multiple versions of ryu is installed on a system.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

ryu/hooks.py

@@ -16,9 +16,25 @@
 # under the License.
 
 import sys
+from setuptools.command import easy_install
 from ryu import version
 
 
+# Global variables in this module doesn't work as we expect
+# because, during the setup procedure, this module seems to be
+# copied (as a file) and can be loaded multiple times.
+# We save them into __main__ module instead.
+def _main_module():
+    return sys.modules['__main__']
+
+
+def save_orig():
+    """Save original easy_install.get_script_args.
+    This is necessary because pbr's setup_hook is sometimes called
+    before ours."""
+    _main_module()._orig_get_script_args = easy_install.get_script_args
+
+
 def setup_hook(config):
     """Filter config parsed from a setup.cfg to inject our defaults."""
     metadata = config['metadata']
@@ -31,3 +47,16 @@ def setup_hook(config):
     config['metadata'] = metadata
 
     metadata['version'] = str(version)
+
+    # pbr's setup_hook replaces easy_install.get_script_args with
+    # their own version, override_get_script_args, prefering simpler
+    # scripts which are not aware of multi-version.
+    # prevent that by doing the opposite.  it's a horrible hack
+    # but we are in patching wars already...
+    from pbr import packaging
+
+    def my_get_script_args(*args, **kwargs):
+        return _main_module()._orig_get_script_args(*args, **kwargs)
+
+    packaging.override_get_script_args = my_get_script_args
+    easy_install.get_script_args = my_get_script_args

setup.py

@@ -21,8 +21,10 @@ except ImportError:
     pass
 
 import setuptools
+import ryu.hooks
 
 
+ryu.hooks.save_orig()
 setuptools.setup(name='ryu',
                  setup_requires=['pbr'],
                  pbr=True)