Make release scripts even more robust.

tools/release/test_scripts.py

Index: tools/release/test_scripts.py
diff --git a/tools/release/test_scripts.py b/tools/release/test_scripts.py
index 3b4da3676cd7e1adb16851a2115ed40bfafe8fce..291ca3812316d57fc4b7a05d5fb625b7d2365788 100644
--- a/tools/release/test_scripts.py
+++ b/tools/release/test_scripts.py
@@ -1406,6 +1406,10 @@ Cr-Commit-Position: refs/heads/4.2.71@{#1}
       Cmd("git status -s -uno", "", cwd=chrome_dir),
       Cmd("git checkout -f master", "", cwd=chrome_dir),
       Cmd("git pull", "", cwd=chrome_dir),
+      Cmd("git branch", "  branch1\n* %s" % TEST_CONFIG["BRANCHNAME"],
+          cwd=chrome_dir),
+      Cmd("git branch -D %s" % TEST_CONFIG["BRANCHNAME"], "",
+          cwd=chrome_dir),
       Cmd("git new-branch %s" % TEST_CONFIG["BRANCHNAME"], "",
           cwd=chrome_dir),
       Cmd("git fetch origin", "", cwd=chrome_v8_dir),