--- a/wutils.py	Thu Mar 13 09:29:47 2014 +0100
+++ b/wutils.py	Thu Mar 13 06:37:04 2014 -0700
@@ -228,3 +228,10 @@
     return run_argv([env['PYTHON'][0]] + execvec, env, cwd=cwd)
 
 
+def uniquify_list(seq):
+    """Remove duplicates while preserving order
+       From Dave Kirby http://www.peterbe.com/plog/uniqifiers-benchmark
+    """
+    seen = set()
+    return [ x for x in seq if x not in seen and not seen.add(x)]
+