Check if triggering PR is in triggered set only if triggered pr exists (otherwise is master sync)
Check if triggering PR is in triggered set only if triggered pr exists (otherwise is master sync)

alexeagle/TypeScript,SaschaNaz/TypeScript,nojvek/TypeScript,RyanCavanaugh/TypeScript,weswigham/TypeScript,nojvek/TypeScript,minestarks/TypeScript,Microsoft/TypeScript,kpreisser/TypeScript,microsoft/TypeScript,nojvek/TypeScript,kpreisser/TypeScript,kitsonk/TypeScript,alexeagle/TypeScript,kpreisser/TypeScript,SaschaNaz/TypeScript,SaschaNaz/TypeScript,alexeagle/TypeScript,RyanCavanaugh/TypeScript,kitsonk/TypeScript,microsoft/TypeScript,SaschaNaz/TypeScript,weswigham/TypeScript,RyanCavanaugh/TypeScript,Microsoft/TypeScript,minestarks/TypeScript,Microsoft/TypeScript,microsoft/TypeScript,minestarks/TypeScript,nojvek/TypeScript,kitsonk/TypeScript,weswigham/TypeScript