fix minor mfs truncate bug

License: MIT
Signed-off-by: Jeromy <jeromyj@gmail.com>

mod/dagmodifier.go

@@ -6,8 +6,8 @@ import (
 	"io"
 	"os"
 
-	proto "gx/ipfs/QmZ4Qi3GaRbjcx28Sme5eMH7RQjGkt8wHxt2a65oLaeFEV/gogo-protobuf/proto"
 	mh "gx/ipfs/QmYf7ng2hG5XBtJA3tN34DQ2GUN5HNksEw1rLDkmr6vGku/go-multihash"
+	proto "gx/ipfs/QmZ4Qi3GaRbjcx28Sme5eMH7RQjGkt8wHxt2a65oLaeFEV/gogo-protobuf/proto"
 	context "gx/ipfs/QmZy2y8t9zQH2a1b8q2ZSLKp17ATuJoCNxxyMFG5qFExpt/go-net/context"
 
 	key "github.com/ipfs/go-ipfs/blocks/key"

mod/dagmodifier_test.go

@@ -447,6 +447,20 @@ func TestDagTruncate(t *testing.T) {
 	if size != 10 {
 		t.Fatal("size was incorrect!")
 	}
+
+	err = dagmod.Truncate(0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	size, err = dagmod.Size()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if size != 0 {
+		t.Fatal("size was incorrect!")
+	}
 }
 
 func TestSparseWrite(t *testing.T) {