Minecraft crashes when a saddled pig you ride dies or when changing between rideable entities

Confirmed.

Note:

Description: Exception in world tick
java.lang.NullPointerException
	at ml.h(SourceFile:1203)
	at sg.a(SourceFile:319)
	at zr.e(SourceFile:878)
	at bdg.e(SourceFile:129)

Reason for this: Minecraft is trying to get the player sat on entity when player has already changed seat.

Bug in the 13w09b too

Reopended, though a different crash report.
Edit: 2 different reports for dying pig and changing entities

Same here. Using my minecart elevator, which requires you to sit in one minecart and enter one above you, crashes the game.

Also happens with multiple players when another player leaves a minecarts sometimes. (Attached another crash report.)

java.lang.NullPointerException
	at sh.a(SourceFile:321)
	at bdb.a(SourceFile:618)
	at fd.a(SourceFile:37)
	at ci.b(SourceFile:350)
	at bdb.d(SourceFile:95)
	at bdj.b(SourceFile:58)

To reproduce the minecart leaving crash described in my previous comment, do this:

1. Build something like in the screenshot 2013-02-28_00.56.29.png.

2. Invite a friend (we did this via LAN - but the crash happened on a dedicated server as well).

3. Place a minecart on one of the two ends, enter it and push the button to start the ride.

4. After arriving at the other end, leave the minecart. All other players will crash. If they did not, remove the minecart again and restart with step 3.

When trying this, it didn't always happen the first time - you'll have to repeat steps 3 and 4 about 1-7 times to cause the crash.

@Mods: I think, using a even more generic title for this ticket would be good.

u: Exception in world tick
at net.minecraft.client.Minecraft.l(SourceFile:1332)
at net.minecraft.client.Minecraft.K(SourceFile:572)
at net.minecraft.client.Minecraft.run(SourceFile:524)

java.lang.NullPointerException
at sh.a(SourceFile:321)
at zs.e(SourceFile:878)
at bdj.e(SourceFile:129)
at bdj.b(SourceFile:179)
at bdb.a(SourceFile:359)
at eo.a(SourceFile:39)
at ch.b(SourceFile:59)
at bdb.d(SourceFile:95)
at bdj.b(SourceFile:58)
at net.minecraft.client.Minecraft.l(SourceFile:1323)
at net.minecraft.client.Minecraft.K(SourceFile:572)
at net.minecraft.client.Minecraft.run(SourceFile:524)
at java.lang.Thread.run(Unknown Source)

Fixed for real this time. I was lazy when I "fixed" it yesterday, sorry.