Tweak setup.py so that it may run even when fired from
different locations, as suggested by Maarten Damen.
diff --git a/setup.py b/setup.py
index 6d6446f..654ab46 100644
--- a/setup.py
+++ b/setup.py
@@ -11,8 +11,9 @@
     os.unlink("MANIFEST")
 
 
+TOPDIR = os.path.dirname(__file__) or "."
 VERSION = re.search('__version__ = "([^"]+)"',
-                    open("dateutil/__init__.py").read()).group(1)
+                    open(TOPDIR + "/dateutil/__init__.py").read()).group(1)
 
 
 setup(name="python-dateutil",