[#129] policer: Use safer defaults

If `processNodes` exits earlier for some reason, `needLocalCopy` could
be false.
See https://github.com/nspcc-dev/neofs-node/issues/2267

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

pkg/services/policer/check.go

@@ -127,7 +127,7 @@ func (p *Policer) processObject(ctx context.Context, addrWithType objectcore.Add
 		p.processNodes(c, addrWithType, nn[i], policy.ReplicaNumberByIndex(i), checkedNodes)
 	}
 
-	if !c.needLocalCopy {
+	if !c.needLocalCopy && c.removeLocalCopy {
 		p.log.Info("redundant local object copy detected",
 			zap.Stringer("object", addr),
 		)
@@ -139,7 +139,11 @@ func (p *Policer) processObject(ctx context.Context, addrWithType objectcore.Add
 type processPlacementContext struct {
 	context.Context
 
+	// needLocalCopy is true if the current node must store an object according to the storage policy.
 	needLocalCopy bool
+	// removeLocalCopy is true if all copies are stored according to the storage policy
+	// and the current node doesn't need to store an object.
+	removeLocalCopy bool
 }
 
 func (p *Policer) processNodes(ctx *processPlacementContext, addrWithType objectcore.AddressWithType,
@@ -242,9 +246,11 @@ func (p *Policer) processNodes(ctx *processPlacementContext, addrWithType object
 	} else if uncheckedCopies > 0 {
 		// If we have more copies than needed, but some of them are from the maintenance nodes,
 		// save the local copy.
-		ctx.needLocalCopy = true
 		p.log.Debug("some of the copies are stored on nodes under maintenance, save local copy",
 			zap.Int("count", uncheckedCopies))
+	} else if uncheckedCopies == 0 {
+		// Safe to remove: checked all copies, shortage == 0.
+		ctx.removeLocalCopy = true
 	}
 }