Skeletons with a sword walk slower if you throw a sword from the same type

Description of the bug

if you throw a sword to a skeleton holding a sword from the same material, the skeleton walk slower and you see many ghost swords under the skeleton glitching until you punch him.

How to recreate

⚠️ This does not always works

1. Find a skeleton that can hold items

2. Throw him a sword with an enchant

3. Throw him a sword from the same material without any enchant

Crash report (F3+C

Minecraft Crash Report ----
// Who set us up the TNT?

Time: 21-7-13 18:12
Description: Manually triggered debug crash

java.lang.Throwable
at ats.k(SourceFile:1238)
at ats.S(SourceFile:663)
at ats.d(SourceFile:619)
at net.minecraft.client.main.Main.main(SourceFile:101)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [bdf['Chrisjosten'/151, l='MpServer', x=-1464,65, y=5,62, z=-300,65]]
Chunk stats: MultiplayerChunkCache: 441
Level seed: 0
Level generator: ID 01 - flat, ver 0. Features enabled: false
Level generator options:
Level spawn location: World: (-1382,4,-277), Chunk: (at 10,0,11 in -87,-18; contains blocks -1392,0,-288 to -1377,255,-273), Region: (-3,-1; contains chunks -96,-32 to -65,-1, blocks -1536,0,-512 to -1025,255,-1)
Level time: 89899 game time, 6198 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
Forced entities: 64 total; [uu['entity.WitherSkull.name'/6, l='MpServer', x=-1528,38, y=20,25, z=-258,03], uu['entity.WitherSkull.name'/7, l='MpServer', x=-1525,00, y=38,69, z=-265,25], uu['entity.WitherSkull.name'/8, l='MpServer', x=-1525,13, y=33,13, z=-245,00], sr['item.item.bone'/14, l='MpServer', x=-1489,44, y=3,13, z=-337,13], sr['item.item.arrow'/15, l='MpServer', x=-1491,97, y=1,13, z=-325,88], sr['item.item.swordDiamond'/1897, l='MpServer', x=-1468,72, y=4,00, z=-300,44], sr['item.item.bone'/16, l='MpServer', x=-1491,50, y=1,13, z=-327,06], sr['item.item.bone'/19, l='MpServer', x=-1477,09, y=4,13, z=-320,09], tq['Skelet'/18, l='MpServer', x=-1494,09, y=4,00, z=-346,66], sr['item.item.arrow'/21, l='MpServer', x=-1476,13, y=4,13, z=-322,59], sr['item.item.arrow'/20, l='MpServer', x=-1476,91, y=4,13, z=-320,06], sr['item.item.chestplateGold'/23, l='MpServer', x=-1476,19, y=4,13, z=-321,84], sr['item.item.bone'/22, l='MpServer', x=-1475,91, y=4,13, z=-321,69], sr['item.item.bone'/25, l='MpServer', x=-1472,88, y=4,13, z=-322,56], sr['item.item.arrow'/24, l='MpServer', x=-1472,91, y=4,13, z=-322,22], sr['item.item.arrow'/27, l='MpServer', x=-1474,94, y=4,13, z=-322,13], sr['item.item.bone'/26, l='MpServer', x=-1473,94, y=4,13, z=-321,72], sr['item.item.bone'/29, l='MpServer', x=-1486,59, y=2,13, z=-329,91], sr['item.item.arrow'/28, l='MpServer', x=-1476,38, y=4,13, z=-321,19], sr['item.item.bone'/31, l='MpServer', x=-1474,19, y=4,13, z=-322,50], sr['item.item.bone'/30, l='MpServer', x=-1473,13, y=3,13, z=-325,25], sr['item.item.bone'/34, l='MpServer', x=-1480,97, y=4,13, z=-324,50], sr['item.item.bone'/35, l='MpServer', x=-1480,84, y=4,13, z=-334,81], sr['item.item.arrow'/32, l='MpServer', x=-1479,75, y=4,13, z=-330,88], sr['item.item.bone'/33, l='MpServer', x=-1479,84, y=4,13, z=-331,94], sr['item.item.bone'/38, l='MpServer', x=-1476,91, y=4,13, z=-328,38], sr['item.item.arrow'/39, l='MpServer', x=-1478,84, y=4,13, z=-329,56], nz['Ervaringsbol'/36, l='MpServer', x=-1481,75, y=4,25, z=-331,03], nz['Ervaringsbol'/37, l='MpServer', x=-1482,03, y=4,25, z=-331,50], sr['item.item.bone'/42, l='MpServer', x=-1482,88, y=3,13, z=-321,69], sr['item.item.arrow'/43, l='MpServer', x=-1473,84, y=4,13, z=-324,81], sr['item.item.bone'/40, l='MpServer', x=-1478,78, y=4,13, z=-329,13], bdf['Chrisjosten'/151, l='MpServer', x=-1464,65, y=5,62, z=-300,65], sr['item.item.arrow'/41, l='MpServer', x=-1478,78, y=4,13, z=-326,28], sr['item.item.bone'/46, l='MpServer', x=-1479,28, y=4,13, z=-325,31], nz['Ervaringsbol'/47, l='MpServer', x=-1479,19, y=4,25, z=-326,69], nz['Ervaringsbol'/44, l='MpServer', x=-1480,09, y=4,25, z=-326,47], sr['item.item.arrow'/45, l='MpServer', x=-1480,03, y=4,13, z=-325,09], sr['item.item.bone'/51, l='MpServer', x=-1475,28, y=4,13, z=-315,28], nz['Ervaringsbol'/50, l='MpServer', x=-1480,97, y=4,25, z=-336,00], sr['item.item.arrow'/49, l='MpServer', x=-1479,94, y=4,13, z=-329,28], sr['item.item.bone'/48, l='MpServer', x=-1481,63, y=4,13, z=-333,75], sr['item.item.arrow'/55, l='MpServer', x=-1472,06, y=4,13, z=-319,53], sr['item.item.arrow'/54, l='MpServer', x=-1478,78, y=4,13, z=-314,94], sr['item.item.arrow'/53, l='MpServer', x=-1478,38, y=4,13, z=-319,53], sr['item.item.bone'/52, l='MpServer', x=-1479,22, y=4,13, z=-319,31], sr['item.item.bone'/59, l='MpServer', x=-1482,16, y=4,13, z=-313,50], sr['item.item.arrow'/58, l='MpServer', x=-1481,69, y=4,13, z=-313,53], sr['item.item.bone'/57, l='MpServer', x=-1472,94, y=4,13, z=-318,19], sr['item.item.bow'/56, l='MpServer', x=-1474,03, y=4,13, z=-319,47], sr['item.item.arrow'/63, l='MpServer', x=-1467,88, y=3,13, z=-332,88], sr['item.item.bone'/62, l='MpServer', x=-1457,91, y=4,13, z=-328,97], sr['item.item.arrow'/61, l='MpServer', x=-1458,75, y=4,13, z=-328,97], sr['item.item.arrow'/68, l='MpServer', x=-1457,47, y=4,13, z=-315,69], sr['item.item.bone'/69, l='MpServer', x=-1470,06, y=4,13, z=-314,66], sr['item.item.arrow'/70, l='MpServer', x=-1469,00, y=4,13, z=-318,16], sr['item.item.bone'/71, l='MpServer', x=-1469,19, y=4,13, z=-317,28], sr['item.item.bone'/64, l='MpServer', x=-1467,88, y=3,13, z=-331,41], sr['item.item.arrow'/65, l='MpServer', x=-1471,19, y=4,13, z=-322,50], sr['item.item.bone'/66, l='MpServer', x=-1471,19, y=4,13, z=-323,06], sr['item.item.arrow'/67, l='MpServer', x=-1469,13, y=4,13, z=-314,88], tr['Slijmkubus'/79, l='MpServer', x=-1440,69, y=1,05, z=-315,31], sr['item.item.bone'/72, l='MpServer', x=-1465,00, y=4,13, z=-311,84], tq['Skelet'/73, l='MpServer', x=-1468,69, y=4,00, z=-300,44]]
Retry entities: 0 total; []
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at bda.a(SourceFile:284)
at ats.b(SourceFile:1761)
at ats.d(SourceFile:628)
at net.minecraft.client.main.Main.main(SourceFile:101)

– System Details –
Details:
Minecraft Version: 1.6.2
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.7.0_11, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 224371248 bytes (213 MB) / 487129088 bytes (464 MB) up to 954466304 bytes (910 MB)
JVM Flags: 1 total; -Xmx1G
AABB Pool Size: 17639 (987784 bytes; 0 MB) allocated, 3 (168 bytes; 0 MB) used
Suspicious classes: No suspicious classes found.
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.6.2
LWJGL: 2.9.0
OpenGL: GeForce GT 540M/PCI/SSE2 GL version 4.1.0, NVIDIA Corporation
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Pack: Default
Current Language: Nederlands (Nederland)
Profiler Position: N/A (disabled)
Vec3 Pool Size: 238 (13328 bytes; 0 MB) allocated, 20 (1120 bytes; 0 MB) used