def handle_merge()

in mozregression/bisector.py [0:0]
56 lines of code
4 McCabe index (conditional complexity)

    def handle_merge(self):
        # let's check if we are facing a merge, and in that case,
        # continue the bisection from the merged branch.
        result = None

        LOG.debug("Starting merge handling...")
        # we have to check the commit of the most recent push
        most_recent_push = self.build_range[1]
        jp = JsonPushes(most_recent_push.repo_name)
        push = jp.push(most_recent_push.changeset, full="1")
        msg = push.changeset["desc"]
        LOG.debug("Found commit message:\n%s\n" % msg)
        branch = find_branch_in_merge_commit(msg, most_recent_push.repo_name)
        if not (branch and len(push.changesets) >= 2):
            # We did not find a branch, lets check the integration branches if we are bisecting m-c
            LOG.debug("Did not find a branch, checking all integration branches")
            if (
                get_name(most_recent_push.repo_name) == "mozilla-central"
                and len(push.changesets) >= 2
            ):
                branch = self._choose_integration_branch(most_recent_push.changeset)
                oldest = push.changesets[0]["node"]
                youngest = push.changesets[-1]["node"]
                LOG.info(
                    "************* Switching to %s by"
                    " process of elimination (no branch detected in"
                    " commit message)" % branch
                )
            else:
                return
        else:
            # so, this is a merge. see how many changesets are in it, if it
            # is just one, we have our answer
            if len(push.changesets) == 2:
                LOG.info(
                    "Merge commit has only two revisions (one of which "
                    "is the merge): we are done"
                )
                return

            # Otherwise, we can find the oldest and youngest
            # changesets, and the branch where the merge comes from.
            oldest = push.changesets[0]["node"]
            # exclude the merge commit
            youngest = push.changesets[-2]["node"]
            LOG.info("************* Switching to %s" % branch)

        # we can't use directly the oldest changeset because we
        # don't know yet if it is good.
        #
        # PUSH1    PUSH2
        # [1 2] [3 4 5 6 7]
        #    G    MERGE  B
        #
        # so first grab the previous push to get the last known good
        # changeset. This needs to be done on the right branch.
        try:
            jp2 = JsonPushes(branch)
            raw = [int(p.push_id) for p in jp2.pushes_within_changes(oldest, youngest)]
            data = jp2.pushes(
                startID=str(min(raw) - 2),
                endID=str(max(raw)),
            )

            older = data[0].changeset
            youngest = data[-1].changeset

            # we are ready to bisect further
            gr, br = self._reverse_if_find_fix(older, youngest)
            result = (branch, gr, br)
        except MozRegressionError:
            LOG.debug("Got exception", exc_info=True)
            raise MozRegressionError(
                "Unable to exploit the merge commit. Origin branch is {}, and"
                " the commit message for {} was:\n{}".format(
                    most_recent_push.repo_name, most_recent_push.short_changeset, msg
                )
            )
        LOG.debug("End merge handling")
        return result