Hello,

lines 1377 to 1383 of l3tl.dtx read

    \tex_ifx:D \l_tl_tmpa_tl \l_tl_tmpb_tl
      \group_end:
      \prg_return_false:
    \tex_else:D
      \group_end:
      \prg_return_false:
    \tex_fi:D

The first \prg_return_false: should be \prg_return_true:.

Regards,
Philipp