True when expr is a tie chain with all leaves in same parent.
That is, True when tie chain crosses no container boundaries, otherwise False.
Example:
abjad> t = Staff(RigidMeasure((2, 8), construct.run(2)) * 2)
abjad> Tie(t.leaves[1:3])
\new Staff {
\time 2/8
c'8
c'8 ~
\time 2/8
c'8
c'8
}
abjad> assert tietools.is_in_same_parent(t.leaves[0].tie.chain)
abjad> assert not tietools.is_in_same_parent(t.leaves[1].tie.chain)
abjad> assert not tietools.is_in_same_parent(t.leaves[2].tie.chain)
abjad> assert tietools.is_in_same_parent(t.leaves[3].tie.chain)