common.py: Fix the build.

Should only use source_info_dict when creating incremental OTAs.

Change-Id: I6a4e5f8fa3613a1b36563ec915e433247965a2b8
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 7bb96a9..cad654a 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -1259,8 +1259,11 @@
     self.path = os.path.join(tmpdir, partition)
     b.Compute(self.path)
 
-    _, self.device = GetTypeAndDevice("/" + partition,
-                                      OPTIONS.source_info_dict)
+    if src is None:
+      _, self.device = GetTypeAndDevice("/" + partition, OPTIONS.info_dict)
+    else:
+      _, self.device = GetTypeAndDevice("/" + partition,
+                                        OPTIONS.source_info_dict)
 
   def WriteScript(self, script, output_zip, progress=None):
     if not self.src: