Renaming a field move its content to first field

Running on fe302a5d1b8ba2b8c398f22c28bdd67357c6f339

How to reproduce:
* Have a note type with fields FIELD1 FIELD2
* Fill FIELD2 with "content 2", leave FIELD1 empty
* Rename FIELD2 to FIELD_2

Expected result:
* First field named FIELD1 has no content,
* Second field named FIELD_2 has content "content 2",

Actual result:
* First field named FIELD1 has content "content 2",
* Second field named FIELD_2 has no content,

Without looking at the code, my assumption is that you use the same behaviour for renaming than for changing note type. Which means that you match field name instead of field position. I really love this change of behavior when it comes to actual change of note type, and it's ideal if you just change field order. But it's clearly not the expected behavior when you rename a field