Placing head in single player sometimes crashes game

Cannot reproduce in that version. However, I notice a lag when the head is placed. Note that I don't receive any message in the launcher console.

Can't reproduce either, but java.util.ConcurrentModificationException is a race condition.
The lag comes maybe from loading the skin from the skin server and may depend on it's utilisation.

Cannot reproduce neighter

Had the same crash when placing my own head:

---- Minecraft Crash Report ----
// Hi. I'm Minecraft, and I'm a crashaholic.

Time: 16/04/14 12:09
Description: Unexpected error

java.util.ConcurrentModificationException
	at java.util.LinkedList$ListItr.checkForComodification(Unknown Source)
	at java.util.LinkedList$ListItr.next(Unknown Source)
	at com.google.common.collect.Iterators$9.next(Iterators.java:939)
	at com.google.common.collect.Iterators.addAll(Iterators.java:357)
	at com.google.common.collect.Lists.newArrayList(Lists.java:147)
	at oy.a(SourceFile:179)
	at oy.c(SourceFile:163)
	at oy.a(SourceFile:116)
	at att.d(SourceFile:88)
	at att.a(SourceFile:77)
	at ahf.a(SourceFile:79)
	at agh.a(SourceFile:122)
	at bqq.a(SourceFile:304)
	at bfr.ak(SourceFile:1256)
	at bfr.p(SourceFile:1602)
	at bfr.ai(SourceFile:801)
	at bfr.f(SourceFile:755)
	at net.minecraft.client.main.Main.main(SourceFile:121)


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

-- Head --
Stacktrace:
	at java.util.LinkedList$ListItr.checkForComodification(Unknown Source)
	at java.util.LinkedList$ListItr.next(Unknown Source)
	at com.google.common.collect.Iterators$9.next(Iterators.java:939)
	at com.google.common.collect.Iterators.addAll(Iterators.java:357)
	at com.google.common.collect.Lists.newArrayList(Lists.java:147)
	at oy.a(SourceFile:179)
	at oy.c(SourceFile:163)
	at oy.a(SourceFile:116)
	at att.d(SourceFile:88)
	at att.a(SourceFile:77)
	at ahf.a(SourceFile:79)
	at agh.a(SourceFile:122)
	at bqq.a(SourceFile:304)
	at bfr.ak(SourceFile:1256)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bsv['Smurfy123Ringo'/63293, l='MpServer', x=-373.16, y=30.99, z=100.08]]
	Chunk stats: MultiplayerChunkCache: 121, 121
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: -255.00,64.00,29.00 - World: (-255,64,29), Chunk: (at 1,4,13 in -16,1; contains blocks -256,0,16 to -241,255,31), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Level time: 262508 game time, 262508 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: true), thunder time: 0 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
	Forced entities: 29 total; [ye['Sheep'/63113, l='MpServer', x=-329.84, y=64.00, z=23.22], zs['Creeper'/83937, l='MpServer', x=-386.81, y=31.00, z=97.78], za['item.item.egg'/95396, l='MpServer', x=-374.63, y=30.00, z=102.59], xu['Chicken'/94443, l='MpServer', x=-391.47, y=32.00, z=95.50], za['item.item.chickenRaw'/95398, l='MpServer', x=-373.22, y=30.00, z=99.78], ye['Sheep'/63128, l='MpServer', x=-317.09, y=65.00, z=21.13], ye['Sheep'/63127, l='MpServer', x=-310.69, y=62.00, z=27.47], aaz['Spider'/95403, l='MpServer', x=-299.50, y=66.00, z=29.50], ye['Sheep'/63138, l='MpServer', x=-311.81, y=61.00, z=32.25], bsv['Smurfy123Ringo'/63293, l='MpServer', x=-373.16, y=30.99, z=100.08], ye['Sheep'/63139, l='MpServer', x=-300.47, y=65.00, z=38.47], ye['Sheep'/63140, l='MpServer', x=-293.00, y=64.00, z=45.00], ye['Sheep'/63141, l='MpServer', x=-295.72, y=67.00, z=37.78], ye['Sheep'/63142, l='MpServer', x=-299.94, y=64.00, z=46.91], ye['Sheep'/63143, l='MpServer', x=-299.09, y=64.00, z=50.09], aar['Skeleton'/95472, l='MpServer', x=-414.50, y=72.00, z=89.50], bsw['VeryCosySlippers'/63915, l='MpServer', x=-336.16, y=33.00, z=-0.69], xu['Chicken'/94321, l='MpServer', x=-375.19, y=30.00, z=102.44], bsw['VeryCosySlippers'/63915, l='MpServer', x=-374.28, y=30.00, z=103.31], xu['Chicken'/94314, l='MpServer', x=-375.81, y=30.00, z=103.38], bsw['VeryCosySlippers'/63915, l='MpServer', x=-272.63, y=76.06, z=-15.72], zs['Creeper'/94187, l='MpServer', x=-359.59, y=32.00, z=95.94], ye['Sheep'/63093, l='MpServer', x=-335.75, y=64.00, z=21.44], ye['Sheep'/63094, l='MpServer', x=-365.09, y=65.00, z=21.09], ye['Sheep'/63095, l='MpServer', x=-375.88, y=66.00, z=28.03], ye['Sheep'/63102, l='MpServer', x=-358.81, y=69.00, z=42.59], ye['Sheep'/63103, l='MpServer', x=-349.50, y=69.00, z=44.50], ye['Sheep'/63098, l='MpServer', x=-355.22, y=69.00, z=42.59], ye['Sheep'/63099, l='MpServer', x=-357.94, y=70.00, z=38.91]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bqr.a(SourceFile:308)
	at bfr.b(SourceFile:2069)
	at bfr.f(SourceFile:769)
	at net.minecraft.client.main.Main.main(SourceFile:121)

-- System Details --
Details:
	Minecraft Version: 14w11b
	Operating System: Windows 8 (amd64) version 6.2
	Java Version: 1.7.0_51, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 206011048 bytes (196 MB) / 602931200 bytes (575 MB) up to 954728448 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Launched Version: 14w11b
	LWJGL: 2.9.1
	OpenGL: Intel(R) HD Graphics GL version 4.0.0 - Build 10.18.10.3282, Intel
	GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Anisotropic filtering is supported and maximum anisotropy is 16.
Shaders are available because OpenGL 2.1 is supported.

	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: English (UK)
	Profiler Position: N/A (disabled)
	Anisotropic Filtering: Off (1)

Cannot reproduce in versions > 14w11b

Cannot confirm for 1.9.3-pre3

Cannot reproduce in 16w42a