Change variable differences page behavior

[CSimmer]

sandaionescu request:
"I think "differences" at field level should not be shown (at least not to a user, or editor) from when there is nothing (i.e. no codebook) to when there is something (i.e. the initial codebook upload) - but only when a change is made to the first/original instance of a codebook. Otherwise it is confusing."

Orginally posed in: can't see crowdsourced edits; official version unviewable

Discussion: Two items to consider.

1. This is a little different behavior than the way git determines changes. It may cause an unintended side effects.
2. It don't think there is a way to determine if this is the first change. I don't think there is an element to store this data. It would have to rely on data outside the xml file. Using git commit history could be a way.
3. Under normal circumstances (multiple servers), the left side would be populated. Don't you want to know this difference?
4. If single server or looking at only local commits, then
   4a) You would not want to show the diff page if commit count is 1 for the file. (Nothing to compare.)
   4b) The labels should change to (Previous vs Current)

QUESTION: Lars, do you want me to add this as an enhancement request?

FYI: At the time this was created, ICPSR was only using demo for testing, so there was nothing to compare.

Example Difference page: https://demo.ncrn.cornell.edu/ced2ar-web/codebooks/icpsr02268-0001/v/v1/vars/V4101/diff