If the reference repo used as basis for a patch
has incomplete history, then there must be
a "tombstone" for the latest missing commit.
Otherwise some ostree operations fail, such
as removing patches from the running system.
Test Plan:
pass - patch contains tombstone
pass - patch removal
Closes-Bug: 2086705
Change-Id: I6a4609e3f668702a15d40cac9e65c13d07850821
Signed-off-by: Leonardo Fagundes Luz Serrano <Leonardo.FagundesLuzSerrano@windriver.com>