[MC-132106] Placing a minecart on a block added to #minecraft:rails via data pack corrupts world

Apply data pack
Shift-click with minecart on repeater.

Result:

(18w30b) crash-2018-07-31_22.31.16-server.txt

Description: Ticking entity

java.lang.ClassCastException: bgt cannot be cast to bci
	at apf.j(SourceFile:640)
	at apf.b(SourceFile:386)
	at apf.R_(SourceFile:307)
	at axv.a(SourceFile:1202)
	at tc.a(SourceFile:577)
	at axv.g(SourceFile:1177)
	at axv.k(SourceFile:1083)
	at axv$$Lambda$1616/505433395.test(Unknown Source)
	at xm.a(SourceFile:209)
	at axv.l(SourceFile:1070)
	at tc.l(SourceFile:493)
	at net.minecraft.server.MinecraftServer.b(SourceFile:736)
	at net.minecraft.server.MinecraftServer.a(SourceFile:661)
	at dga.a(SourceFile:159)
	at net.minecraft.server.MinecraftServer.run(SourceFile:564)
	at java.lang.Thread.run(Thread.java:745)

This error happens every time when trying to open the world afterwards.
Removing the pack from the datapacks folder fixes the world.