Fix PR checks (dotnet#1965)

Allow PR builds to flow

Author: ryanbrandenburg

Infrastructure/src/TriageBuildFailures/Commands/Triage.cs

@@ -143,7 +143,7 @@ private async Task<IEnumerable<ICIBuild>> GetUntriagedBuildFailures()
 
         private bool IsWatchedBuild(ICIBuild build)
         {
-            if (_watchedBranches.Any(b => build.Branch.StartsWith(b, StringComparison.OrdinalIgnoreCase)))
+            if (_watchedBranches.Any(b => build.Branch.StartsWith(b, StringComparison.OrdinalIgnoreCase)) || build.Branch.StartsWith("refs/pull", StringComparison.OrdinalIgnoreCase))
             {
                 return true;
             }

Infrastructure/src/TriageBuildFailures/GitHub/PullRequestClient.cs

@@ -30,7 +30,7 @@ public Task<string> GetBuildLogAsync(ICIBuild build)
         public async Task<IEnumerable<ICIBuild>> GetFailedBuildsAsync(DateTime startDate)
         {
             var prs = await _gitHubClient.GetPullRequests("aspnet", "AspNetCore");
-
+            prs = prs.Where(pr => pr.UpdatedAt >= startDate);
             var builds = new List<VSTSBuild>();
             foreach (var pr in prs)
             {
@@ -67,7 +67,7 @@ public Task<IEnumerable<ICITestOccurrence>> GetTestsAsync(ICIBuild build, BuildS
         public async Task SetTagAsync(ICIBuild build, string tag)
         {
             var vstsBuild = (VSTSBuild)build;
-            if(vstsBuild.PRSource != null && string.Equals(tag, Triage.TriagedTag))
+            if (vstsBuild.PRSource != null && string.Equals(tag, Triage.TriagedTag))
             {
                 var comment = "I've triaged the above build.";
                 await _gitHubClient.CreateComment(vstsBuild.PRSource, comment);