Backport c120882 from trunk

CHANGES.txt

@@ -4,6 +4,8 @@ Change History
 1.4.5 (unreleased)
 ==================
 
+- Remove duplicate path from script's sys.path setup.
+
 Bugs fixed:
 
 - In the download module, fixed the handling of directories that are pointed

src/zc/buildout/easy_install.py

@@ -915,7 +915,12 @@ def scripts(reqs, working_set, executable, dest,
 
     path = [dist.location for dist in working_set]
     path.extend(extra_paths)
-    path = map(realpath, path)
+    # order preserving unique
+    unique_path = []
+    for p in path:
+        if p not in unique_path:
+            unique_path.append(p)
+    path = map(realpath, unique_path)
 
     generated = []