Strange issue with ChangeLog in git

[Colin Law]

I have a very strange issue with the file ChangeLog in git.  Around a
week ago I forked the git repo and started a branch off maint for some
development.  Now when I look at the changes between my working copy
and the repository I find that somehow a chunk has been added to the
start of ChangeLog in my working copy.

My copy of ChangeLog starts
2016-04-10 Per Johansson
    * Added new sv_AX and sv_FI account plans. (HEAD -> maint, origin/maint)

Then there are number of entries and then
2016-03-24 Geert Janssens
    * Bug 693342 - Print (bottom) prints to middle for 3-check pages

Whereas the version in the git repository has not got the first
entries at all, and starts with
 2016-03-24 Geert Janssens
    * Bug 693342 - Print (bottom) prints to middle for 3-check pages
(HEAD, origin/maint, maint)

There is no way that I added the extra lines so I am completely at a
loss to understand what is going on.

Colin