fix typo (leftover from some debugging code)

Change-Id: I29a42820ccf8567508f1aeefcc89c2462e9ad43c
diff --git a/tools/releasetools/ota_from_target_files b/tools/releasetools/ota_from_target_files
index 0454d6f..ba29f9b 100755
--- a/tools/releasetools/ota_from_target_files
+++ b/tools/releasetools/ota_from_target_files
@@ -153,7 +153,7 @@
       suffix = { False: "", True: "/" }
       input = "".join(["%s%s\n" % (i.name, suffix[i.dir])
                        for i in cls.ITEMS.itervalues() if i.name])
-      output2, error = p.communicate(input)
+      output, error = p.communicate(input)
       assert not error
 
     for line in output.split("\n"):