[datastore] Fix querying with []byte.

impl/prod/raw_datastore.go

 // Copyright 2015 The LUCI Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 183 matching lines @@
                         }
                         ret = ret.Ancestor(p.Value.(*datastore.Key))
                 } else {
                         filt := prop + "="
                         for _, v := range vals {
                                 p, err := dsF2RProp(d.aeCtx, v)
                                 if err != nil {
                                         return nil, err
                                 }
 
+                                // Filter doesn't like ByteString, even though ByteString is the indexed
+                                // counterpart of []byte... sigh.
+                                if ds, ok := p.Value.(datastore.ByteString); ok {
+                                        p.Value = []byte(ds)
+                                }
                                 ret = ret.Filter(filt, p.Value)
                         }
                 }
         }
 
         if lnam, lop, lprop := fq.IneqFilterLow(); lnam != "" {
                 p, err := dsF2RProp(d.aeCtx, lprop)
                 if err != nil {
                         return nil, err
                 }
@@ skipping 107 matching lines @@
                 return struct{}{}
         }
         return nil
 }
 
 func (d *rdsImpl) Constraints() ds.Constraints { return constraints.DS() }
 
 func (d *rdsImpl) GetTestable() ds.Testable {
         return nil
 }