Dynamic template ref name doesn't work since 3.2.25 version

[mateuszkulpa]

Version

3.2.25

Reproduction link

sfc.vuejs.org/

Steps to reproduce

1. Open link to SFC Playground.

2. Change version of vue to 2.2.25

3. Open console, you will see that refs values have undefined value

input 1: undefined
input 2: undefined

4. Change version to 2.2.24, in console you will see that input1 and input2 values contain html element

input 1: <input ref_for=​"true">​
input 2: <input ref_for=​"true">​

What is expected?

Dynamic template ref names should work as before.

What is actually happening?

Dynamic template ref (with dynamic name) stopped work since 3.2.25 version