dep: Make SafeWriter use status map for OnChanged

If vendor was empty, nonexistent, or just missing a few targeted items,
the SafeWriter would miss them.

cmd/dep/ensure.go

@@ -316,7 +316,7 @@ func (cmd *ensureCommand) runVendorOnly(ctx *dep.Ctx, args []string, p *dep.Proj
 
 	// Pass the same lock as old and new so that the writer will observe no
 	// difference, and write out only ncessary vendor/ changes.
-	dw, err := dep.NewSafeWriter(nil, p.Lock, p.Lock, dep.VendorAlways, p.Manifest.PruneOptions)
+	dw, err := dep.NewSafeWriter(nil, p.Lock, p.Lock, dep.VendorAlways, p.Manifest.PruneOptions, nil)
 	//dw, err := dep.NewDeltaWriter(p.Lock, p.Lock, p.Manifest.PruneOptions, filepath.Join(p.AbsRoot, "vendor"), dep.VendorAlways)
 	if err != nil {
 		return err

cmd/dep/init.go

@@ -170,7 +170,7 @@ func (cmd *initCommand) Run(ctx *dep.Ctx, args []string) error {
 		ctx.Err.Printf("Old vendor backed up to %v", vendorbak)
 	}
 
-	sw, err := dep.NewSafeWriter(p.Manifest, nil, p.Lock, dep.VendorAlways, p.Manifest.PruneOptions)
+	sw, err := dep.NewSafeWriter(p.Manifest, nil, p.Lock, dep.VendorAlways, p.Manifest.PruneOptions, nil)
 	if err != nil {
 		return errors.Wrap(err, "init failed: unable to create a SafeWriter")
 	}

txn_writer.go

@@ -90,7 +90,7 @@ type SafeWriter struct {
 // - If oldLock is provided without newLock, error.
 //
 // - If vendor is VendorAlways without a newLock, error.
-func NewSafeWriter(manifest *Manifest, oldLock, newLock *Lock, vendor VendorBehavior, prune gps.CascadingPruneOptions) (*SafeWriter, error) {
+func NewSafeWriter(manifest *Manifest, oldLock, newLock *Lock, vendor VendorBehavior, prune gps.CascadingPruneOptions, status map[string]verify.VendorStatus) (*SafeWriter, error) {
 	sw := &SafeWriter{
 		Manifest:     manifest,
 		lock:         newLock,
@@ -114,7 +114,18 @@ func NewSafeWriter(manifest *Manifest, oldLock, newLock *Lock, vendor VendorBeha
 	case VendorAlways:
 		sw.writeVendor = true
 	case VendorOnChanged:
-		sw.writeVendor = sw.lockDiff.Changed(anyExceptHash & ^verify.InputImportsChanged) || (newLock != nil && oldLock == nil)
+		if newLock != nil && oldLock == nil {
+			sw.writeVendor = true
+		} else if sw.lockDiff.Changed(anyExceptHash & ^verify.InputImportsChanged) {
+			sw.writeVendor = true
+		} else {
+			for _, stat := range status {
+				if stat != verify.NoMismatch {
+					sw.writeVendor = true
+					break
+				}
+			}
+		}
 	}
 
 	if sw.writeVendor && newLock == nil {
@@ -442,7 +453,7 @@ func NewDeltaWriter(oldLock, newLock *Lock, status map[string]verify.VendorStatu
 	if err != nil && os.IsNotExist(err) {
 		// Provided dir does not exist, so there's no disk contents to compare
 		// against. Fall back to the old SafeWriter.
-		return NewSafeWriter(nil, oldLock, newLock, behavior, prune)
+		return NewSafeWriter(nil, oldLock, newLock, behavior, prune, status)
 	}
 
 	sw.lockDiff = verify.DiffLocks(oldLock, newLock)