Restrict git describe to tags matching v*

Signed-off-by: Michael Marchetti <mmarchetti@sandvine.com>
diff --git a/setup_lite.py b/setup_lite.py
index 7bb1c79..23d224c 100755
--- a/setup_lite.py
+++ b/setup_lite.py
@@ -41,7 +41,7 @@
 __scripts__ = ['openflow-lib']
 
 setup(name=__name,
-      version_command=('git describe', 'pep440-git'),
+      version_command=('git describe --match v*', 'pep440-git'),
       description=__description,
       long_description=__description,
       author=__author,