[ktp-auth-handler] Fixed uninitialized variable usage
Review Request #129016 - Created Sept. 25, 2016 and submitted
If there is no account (condition at 175 is false), then
SignOn::Identity *identitywill be used without initialization at line 210.
Bug reported by the clang static analyzer.
Thanks to Aleix Pol Gonzalez for the idea to run the analyzer. :)