Address comments

codegen/builtin_fs.go

@@ -475,6 +475,7 @@ func (m Copy) Call(ctx context.Context, cln *client.Client, ret Register, opts O
 	)
 	fs.SolveOpts = append(fs.SolveOpts, input.SolveOpts...)
 	fs.SessionOpts = append(fs.SessionOpts, input.SessionOpts...)
+	commitHistory(fs.Image, false, "COPY %s %s", src, dest)
 
 	return ret.Set(fs)
 }
@@ -518,6 +519,10 @@ func (l Label) Call(ctx context.Context, cln *client.Client, ret Register, opts
 
 	fs.Image.Config.Labels[key] = value
 
+	// In Dockerfile, multiple labels can be specified in the same LABEL command
+	// leading to one history element. This checks if the previous history
+	// committed was also a label, in which case it should just add to the
+	// previous history element.
 	numHistory := len(fs.Image.History)
 	if numHistory > 0 && strings.HasPrefix(fs.Image.History[numHistory-1].CreatedBy, "LABEL") {
 		fs.Image.History[numHistory-1].CreatedBy = fmt.Sprintf("%s %s=%s", fs.Image.History[numHistory-1].CreatedBy, key, value)