[Bugfix] Check for presence before moving

There are vendor products but no *.map situation

Signed-off-by: jiangxu5 <jiangxu5@xiaomi.com>
Change-Id: I5068abd1f81bca53ffcbdd415874b8fb49408e30
diff --git a/tools/releasetools/merge/merge_target_files.py b/tools/releasetools/merge/merge_target_files.py
index c06fd4c..c95cead 100755
--- a/tools/releasetools/merge/merge_target_files.py
+++ b/tools/releasetools/merge/merge_target_files.py
@@ -149,6 +149,13 @@
 OPTIONS.vendor_dexpreopt_config = None
 
 
+def move_only_exists(source, destination):
+  """Judge whether the file exists and then move the file."""
+
+  if os.path.exists(source):
+    shutil.move(source, destination)
+
+
 def create_merged_package(temp_dir):
   """Merges two target files packages into one target files structure.
 
@@ -286,9 +293,8 @@
   shutil.move(
       os.path.join(vendor_target_files_dir, 'IMAGES', partition_img),
       os.path.join(target_files_dir, 'IMAGES', partition_img))
-  shutil.move(
-      os.path.join(vendor_target_files_dir, 'IMAGES', partition_map),
-      os.path.join(target_files_dir, 'IMAGES', partition_map))
+  move_only_exists(os.path.join(vendor_target_files_dir, 'IMAGES', partition_map),
+        os.path.join(target_files_dir, 'IMAGES', partition_map))
 
   def copy_recovery_file(filename):
     for subdir in ('VENDOR', 'SYSTEM/vendor'):