Revert back to use exec() instead of execfile().

drover.py

Index: drover.py
diff --git a/drover.py b/drover.py
index 2f726a5d19fdc6b0a9c6f2022694bfdae7732c8e..8a56e2a3e21f22aa4bc7ce8907e7a2535123dce1 100755
--- a/drover.py
+++ b/drover.py
@@ -403,7 +403,9 @@ def drover(options, args):
   global file_pattern_
   if os.path.exists("drover.properties"):
     FILE_PATTERN = file_pattern_
-    execfile("drover.properties")
+    f = open("drover.properties")
+    exec(f)
+    f.close()
     if FILE_PATTERN:
       file_pattern_ = FILE_PATTERN