before this change, we suse `git submodule summary ${submodule}`
for collecting the titles of commits in between current HEAD and
origin/master. normally, this works just fine. but it fails to
collect all commits if the origin/master happens to reference
a merge commit. for instance, if we have following history like:
1. merge foo
2. bar
3. foo
4. baz <--- submodule is pointing here.
`git submodule summary` would just print out the titles of commits
of 1 and 3.
so, in this change, instead of relying on `git submodule summary`,
we just collect the commits using `git log`. but we preserve the
output format used by `git submodule summary` to be consistent with
the previous commits bumping up the submodules. please note, in
this change instead of matching the output of `git submodule summary`,
we use `git merge-base --is-ancestor HEAD origin/master` to check
if we are going to create a fastforward change, this is less fragile.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closes#13366
0d4ffe1d69