Fix merge-to-branch imports.

BUG=
TBR=ulan@chromium.org

Review URL: https://codereview.chromium.org/170513002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19448 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

tools/push-to-trunk/merge_to_branch.py

@@ -27,6 +27,8 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 from collections import OrderedDict
+import optparse
+import sys
 
 from common_includes import *