'b' disappears because it's not involved in a conflict anymore.
So --reprocess --show-base could give:
a <<<< d ||||| ===== x >>>>> e f <<<<< ||||| ===== y >>>>> c
'b' disappears because it's not involved in a conflict anymore.
So --reprocess --show-base could give:
a
<<<<
d
|||||
=====
x
>>>>>
e
f
<<<<<
|||||
=====
y
>>>>>
c