misc/dashboard: cope with removed Package fields.

adg removed some now-unwanted fields in Package a while ago,
but there are still datastore entities with those fields,
so we must explicitly check for ErrFieldMismatch and ignore it.

R=golang-dev, rsc
CC=adg, golang-dev
https://golang.org/cl/6007043

misc/dashboard/app/build/build.go

@@ -49,6 +49,10 @@ func (p *Package) LastCommit(c appengine.Context) (*Commit, error) {
 		Order("-Time").
 		Limit(1).
 		GetAll(c, &commits)
+	if _, ok := err.(*datastore.ErrFieldMismatch); ok {
+		// Some fields have been removed, so it's okay to ignore this error.
+		err = nil
+	}
 	if err != nil {
 		return nil, err
 	}
@@ -65,6 +69,10 @@ func GetPackage(c appengine.Context, path string) (*Package, error) {
 	if err == datastore.ErrNoSuchEntity {
 		return nil, fmt.Errorf("package %q not found", path)
 	}
+	if _, ok := err.(*datastore.ErrFieldMismatch); ok {
+		// Some fields have been removed, so it's okay to ignore this error.
+		err = nil
+	}
 	return p, err
 }
 
@@ -297,7 +305,12 @@ func Packages(c appengine.Context, kind string) ([]*Package, error) {
 	q := datastore.NewQuery("Package").Filter("Kind=", kind)
 	for t := q.Run(c); ; {
 		pkg := new(Package)
-		if _, err := t.Next(pkg); err == datastore.Done {
+		_, err := t.Next(pkg)
+		if _, ok := err.(*datastore.ErrFieldMismatch); ok {
+			// Some fields have been removed, so it's okay to ignore this error.
+			err = nil
+		}
+		if err == datastore.Done {
 			break
 		} else if err != nil {
 			return nil, err

misc/dashboard/app/build/init.go

@@ -42,7 +42,12 @@ func initHandler(w http.ResponseWriter, r *http.Request) {
 	c := appengine.NewContext(r)
 	defer cache.Tick(c)
 	for _, p := range defaultPackages {
-		if err := datastore.Get(c, p.Key(c), new(Package)); err == nil {
+		err := datastore.Get(c, p.Key(c), new(Package))
+		if _, ok := err.(*datastore.ErrFieldMismatch); ok {
+			// Some fields have been removed, so it's okay to ignore this error.
+			err = nil
+		}
+		if err == nil {
 			continue
 		} else if err != datastore.ErrNoSuchEntity {
 			logErr(w, r, err)