Fix build.

Change-Id: Id3eb4821a3c3061063a00294bfa268693c773eb8
diff --git a/tools/releasetools/sparse_img.py b/tools/releasetools/sparse_img.py
index d2955c3..78f3057 100644
--- a/tools/releasetools/sparse_img.py
+++ b/tools/releasetools/sparse_img.py
@@ -204,9 +204,9 @@
     assert zero_blocks or nonzero_blocks
 
     if zero_blocks:
-      out["__ZERO"] = RangeSet(data=zero_blocks)
+      out["__ZERO"] = rangelib.RangeSet(data=zero_blocks)
     if nonzero_blocks:
-      out["__NONZERO"] = RangeSet(data=nonzero_blocks)
+      out["__NONZERO"] = rangelib.RangeSet(data=nonzero_blocks)
 
   def ResetFileMap(self):
     """Throw away the file map and treat the entire image as