Maybe a bug with slurs

[Павел]

See these two examples. They are almost same except angle brackets. In 
first example slur behaves correctly, but in second does not.

\version "2.20.0"
{
    \new Voice = "first" { g'8 f'( }
    \context Voice = "first" << <e')>4 <b b'> >>
    \new Voice = "second" { g'8 f'( }
    \context Voice = "second" << e'4) <b b'> >>
}