[perf] Be robust to androidbuildinternal API returning 0 items.

Change-Id: I9f09a239b75af61559fcb3ec076f087ac750ba93
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/793296
Commit-Queue: Joe Gregorio <jcgregorio@google.com>
Reviewed-by: Ravi Mistry <rmistry@google.com>
diff --git a/android_ingest/go/buildapi/buildapi.go b/android_ingest/go/buildapi/buildapi.go
index 0e6e0b2..0cb9937 100644
--- a/android_ingest/go/buildapi/buildapi.go
+++ b/android_ingest/go/buildapi/buildapi.go
@@ -59,6 +59,9 @@
 		return -1, -1, skerr.Wrap(err)
 	}
 	sklog.Infof("Got %d items.", len(resp.Builds))
+	if len(resp.Builds) == 0 {
+		return 0, 0, skerr.Fmt("androidbuildinteral returned no results.")
+	}
 	build := resp.Builds[0]
 	// Convert build.BuildId to int64.
 	buildId, err := strconv.ParseInt(build.BuildId, 10, 64)