Fix test flake

Test: th
Bug: 289013326
Change-Id: Ib233978ff861b010bdc3bd1a02ea9baefe6a3489
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 5d102cd..39e1bdd 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -1424,9 +1424,10 @@
   def ResolveBinaryPath(path):
     if os.path.exists(path):
       return path
-    new_path = os.path.join(OPTIONS.search_path, path)
-    if os.path.exists(new_path):
-      return new_path
+    if OPTIONS.search_path:
+      new_path = os.path.join(OPTIONS.search_path, path)
+      if os.path.exists(new_path):
+        return new_path
     raise ExternalError(
         "Failed to find {}".format(new_path))