"""

        Load context data needed for generating compare diff

        :param pull_request:

        """

        c.org_repo = pull_request.org_repo

        (c.org_ref_type,

         c.org_ref_name,

         c.org_rev) = pull_request.org_ref.split(':')

        c.other_repo = pull_request.other_repo

        (c.other_ref_type,

         c.other_ref_name,

         c.other_rev) = pull_request.other_ref.split(':') # other_rev is ancestor

        org_scm_instance = c.org_repo.scm_instance # property with expensive cache invalidation check!!!

        c.cs_repo = c.org_repo

        c.cs_ranges = [org_scm_instance.get_changeset(x) for x in pull_request.revisions]

        c.cs_ranges_org = None # not stored and not important and moving target - could be calculated ...

        revs = [ctx.revision for ctx in reversed(c.cs_ranges)]

        c.jsdata = json.dumps(graph_data(org_scm_instance, revs))

        c.available = []

        c.org_branch_name = c.org_ref_name

        if org_scm_instance.alias == 'hg' and c.other_ref_name != 'ancestor':

            if c.org_ref_type != 'branch':

                c.org_branch_name = org_scm_instance.get_changeset(c.org_ref_name).branch # use ref_type ?

            other_branch_name = c.other_ref_name

            if c.other_ref_type != 'branch':

            # candidates: descendants of old head that are on the right branch

            #             and not are the old head itself ...

            #             and nothing at all if old head is a descendent of target ref name

        raw_ids = [x.raw_id for x in c.cs_ranges]

        c.cs_comments = c.org_repo.get_comments(raw_ids)

        c.statuses = c.org_repo.statuses(raw_ids)

        ignore_whitespace = request.GET.get('ignorews') == '1'

        line_context = request.GET.get('context', 3)

        c.ignorews_url = _ignorews_url

        c.context_url = _context_url

        c.fulldiff = request.GET.get('fulldiff')

        diff_limit = self.cut_off_limit if not c.fulldiff else None

        # we swap org/other ref since we run a simple diff on one repo

        log.debug('running diff between %s and %s in %s'

                  % (c.other_rev, c.org_rev, org_scm_instance.path))

        txtdiff = org_scm_instance.get_diff(rev1=safe_str(c.other_rev), rev2=safe_str(c.org_rev),

                                      ignore_whitespace=ignore_whitespace,

                                      context=line_context)

        diff_processor = diffs.DiffProcessor(txtdiff or '', format='gitdiff',

                                             diff_limit=diff_limit)

        _parsed = diff_processor.prepare()

        c.limited_diff = False