Bug 158698

Description:
- I start by opening a template CSV file, that only has the 1st line (my headers) filled, in LibreOffice.
- I then copy from another spreadsheet (doesn't matter what the format is—tried XLSX, CSV, etc; doesn't matter what the application is—tried LibreOffice and MS Excel, it even happens when I copy columns from the same sheet): I repeat this process as many times as needed:
  - Select one source column from source spreadsheet (whatever application & format) and then select destination column in LibreOffice (click on header) and paste as 'Unformatted Text' via context menu on selection.
- When done, LibreOffice indicates that the file has changed (for example, the red dot of the 'Save' icon appears) but when I save the file (through 'Save' icon or 'File' > 'Save' menu) none of the changes are saved. This also applies to 'Save As' if I save it as a CSV file with another name, and to the 'Save' option that appears if I try to close the unsaved file.
However, if I manually edit even one cell or make another change or if I copy even one cell with formatting, changes are saved in CSV format (i.e. this only happens when I make ALL changes as copying-pasting of 'Unformatted Text').
Note that, if I save it as a different format (like XLSX) the changes are saved.

Another version I verified having this issue is 7.5.8.2. This is a problem that has appeared at least a few releases back but I didn't record when I first noticed it. 

Steps to Reproduce:
1. Start by opening a template CSV file, that only has the 1st line filled, in LibreOffice.
2. Copy from another spreadsheet by selecting one source column from source spreadsheet (whatever application & format) and then select destination column in LibreOffice (click on header) and paste as 'Unformatted Text' via context menu on selection.
3. When done, save the file.

Actual Results:
Changes are not saved

Expected Results:
Changes should be saved


Reproducible: Always


User Profile Reset: No

Additional Info:
See description. It appears this only applies when all changes are as copying-pasting of 'Unformatted Text'