def _isfullcopytraceable(repo, c1, base):
    """ Checks that if base, source and destination are all no-public branches,
    if yes let's use the full copytrace algorithm for increased capabilities
    since it will be fast enough.

    `experimental.copytrace.sourcecommitlimit` can be used to set a limit for
    number of changesets from c1 to base such that if number of changesets are
    more than the limit, full copytracing algorithm won't be used.
    """
    if c1.rev() is None:
        c1 = c1.p1()
    if c1.mutable() and base.mutable():
        sourcecommitlimit = repo.ui.configint(b'experimental',
            b'copytrace.sourcecommitlimit')
        commits = len(repo.revs(b'%d::%d', base.rev(), c1.rev()))
        return commits < sourcecommitlimit
    return False
