Only insert outputversion as a preferred mapping type if no error occurs

Some types will be looked up based on their internal type, which is passed
directly to RESTMapping(). RESTMapping() will search the entire version
list if no external types are passed, but OutputVersionMapper was bypassing
that because the default type was always present.

Change OutputVersionMapper to collapse empty versions, and when no external
type is specified, try with the preferred version and then try without.

pkg/kubectl/kubectl.go

@@ -63,7 +63,20 @@ type OutputVersionMapper struct {
 
 // RESTMapping implements meta.RESTMapper by prepending the output version to the preferred version list.
 func (m OutputVersionMapper) RESTMapping(kind string, versions ...string) (*meta.RESTMapping, error) {
-	preferred := append([]string{m.OutputVersion}, versions...)
+	preferred := []string{m.OutputVersion}
+	for _, version := range versions {
+		if len(version) > 0 {
+			preferred = append(preferred, version)
+		}
+	}
+	// if the caller wants to use the default version list, try with the preferred version, and on
+	// error, use the default behavior.
+	if len(preferred) == 1 {
+		if m, err := m.RESTMapper.RESTMapping(kind, preferred...); err == nil {
+			return m, nil
+		}
+		preferred = nil
+	}
 	return m.RESTMapper.RESTMapping(kind, preferred...)
 }