Creates img.zip from target files zip, not dir.

Directory support for img_from_target_files was dropped in aosp/1095755.

Test: Create & boot a merged build.
Change-Id: Ib976ea60a24c2f172c597130d6bcce25199a93b3
diff --git a/tools/releasetools/merge_target_files.py b/tools/releasetools/merge_target_files.py
index 61c4f4e..ba70986 100755
--- a/tools/releasetools/merge_target_files.py
+++ b/tools/releasetools/merge_target_files.py
@@ -914,11 +914,6 @@
 
   generate_super_empty_image(output_target_files_temp_dir, output_super_empty)
 
-  if output_img:
-    # Create the IMG package from the merged target files (before zipping, in
-    # order to avoid an unnecessary unzip and copy).
-    img_from_target_files.main([output_target_files_temp_dir, output_img])
-
   # Finally, create the output target files zip archive and/or copy the
   # output items to the output target files directory.
 
@@ -932,6 +927,11 @@
                                            output_target_files_temp_dir,
                                            temp_dir)
 
+  # Create the IMG package from the merged target files package.
+
+  if output_img:
+    img_from_target_files.main([output_zip, output_img])
+
   # Create the OTA package from the merged target files package.
 
   if output_ota: