add option to specify updater binary, for development

Change-Id: I5f239afff70c87fb16ddc4b8abefa7bbcda6040d
diff --git a/tools/releasetools/edify_generator.py b/tools/releasetools/edify_generator.py
index a5340a0..7978062 100644
--- a/tools/releasetools/edify_generator.py
+++ b/tools/releasetools/edify_generator.py
@@ -305,7 +305,7 @@
     if input_path is None:
       data = input_zip.read("OTA/bin/updater")
     else:
-      data = open(os.path.join(input_path, "updater")).read()
+      data = open(input_path, "rb").read()
     common.ZipWriteStr(output_zip, "META-INF/com/google/android/update-binary",
                        data, perms=0755)