cmd/watchflakes: look for both gitilesCommit and gitiles_commit

The JSON describing a build changed, slightly.
Old convention was camel case, new convention is snake case.

I don't know for sure, but allegedly
Fixes golang/go#69609.

Change-Id: Ic998e0aa3922749f36528d1f7c4fe4cbe6fc690f
Reviewed-on: https://go-review.googlesource.com/c/build/+/615515
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>

Author: dr2chase

cmd/watchflakes/luci.go

@@ -355,7 +355,12 @@ func (c *LUCIClient) GetBuildResult(ctx context.Context, repo string, builder Bu
 	var commit, goCommit string
 	prop := b.GetOutput().GetProperties().GetFields()
 	for _, s := range prop["sources"].GetListValue().GetValues() {
-		x := s.GetStructValue().GetFields()["gitilesCommit"].GetStructValue().GetFields()
+		fm := s.GetStructValue().GetFields()
+		gc := fm["gitilesCommit"]
+		if gc == nil {
+			gc = fm["gitiles_commit"]
+		}
+		x := gc.GetStructValue().GetFields()
 		c := x["id"].GetStringValue()
 		switch bRepo := x["project"].GetStringValue(); bRepo {
 		case repo: