crash when bad branch name is passed to prh as -upto option

[SiavashB]

➜ android git:(sb_build_warnings) prh -upto stagng -m "https://www.pivotaltracker.com/story/show/147770159"

No file has been added, would you like to continue creating PR (y/n)? y
Branch sb_build_warnings set up to track remote branch sb_build_warnings from origin.
Everything up-to-date
Error:
Traceback (most recent call last):
File "/usr/local/bin/prh", line 883, in
sys.exit(main(parse_arguments()))
File "/usr/local/bin/prh", line 675, in main
print process_to_parent(branch_origin, branch_parent, is_add_all, is_just_pr, file_paths, user_input)
File "/usr/local/bin/prh", line 542, in process_to_parent
or create_pull_request(origin, parent, user_input)
File "/usr/local/bin/prh", line 447, in create_pull_request
print "Error:", e["message"]
KeyError: 'message'