I've tested again and again on iOS 8.4 Beta 3, and the text string has never crashed my iPhone. I'm curious if it's limited to certain devices, if I'm Doing It Wrong, or if it's a bunch of people on an older version of iOS 8.x.
I have a 64GB 6 plus and a 128 GB iPad Air 2... Both with 8.4 beta 3.... The bug crashes both devices.