Bukkit/CraftBukkit — comment on commit 81df7590c381e5df2036152c3abc7e6c94f745fe
File: src/main/java/net/minecraft/server/MinecraftServer.java line 114
By nickpoorman:

no String replace returns a new String with the replacement: http://docs.oracle.com/javase/6/docs/api/java/lang/String.html#replace(java.lang.CharSequence, java.lang.CharSequence)