git add -p breaks after split on change at the top of the file

Hello,

The following session reproduces the issue with Git 2.14.1:

    $ git init test
    $ cd test
    $ echo x >file
    $ git add file
    $ git commit -m commit
    $ printf 'a\nb\nx\nc\n' >file

    $ git add -p
    diff --git a/file b/file
    index 587be6b..74a69a0 100644
    --- a/file
    +++ b/file
    @@ -1 +1,4 @@
    +a
    +b
     x
    +c
    Stage this hunk [y,n,q,a,d,/,s,e,?]? <-- press s
    Split into 2 hunks.
    @@ -1 +1,3 @@
    +a
    +b
     x
    Stage this hunk [y,n,q,a,d,/,j,J,g,e,?]? <-- press e

    Now delete the line "+a" in your editor and save.

    error: patch failed: file:1
    error: file: patch does not apply

I expected git add -p to stage this change without error. It works fine without splitting the hunk (by deleting the first and last + line in the diff).

Regards Simon