Please describe the problem:
When inserting a file into an unsaved file, not only the inserted file is deleted but also the line just after the inserted file belonging to the original unsaved file.

Note that if the original file is saved on disk before the insertion, the undo mechanism behaves correctly.

Steps to reproduce:
1. Open a new file
2. Type two lines in it, say:
aaa
bbb
3. Move the cursor to the end of the first line
4. Go to the File->Insert menu
5. Choose a file to insert
The file is inserted correctly
6. Click on Undo




Actual results:
The inserted file is deleted from the document and the bbb line also.

Expected results:
Just the inserted file deleted, not the bbb line.

Does this happen every time?
Yes.

Other information:
Bugs http://bugzilla.gnome.org/show_bug.cgi?id=340262 and http://bugzilla.gnome.org/show_bug.cgi?id=340263 may be related.