abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOP

Test 1: Simple breakindent
    abcd
    qrst
    GHIJ

Test 2: Simple breakindent + sbr=>>
    abcd
    >>qr
    >>EF

Test 3: Simple breakindent + briopt:sbr
    abcd
++  qrst
++  GHIJ

Test 4: Simple breakindent + min width: 18
    abcd
  qrstuv
  IJKLMN

 Test 5: Simple breakindent + shift by 2
    abcd
      qr
      EF

 Test 6: Simple breakindent + shift by -1
    abcd
   qrstu
   HIJKL

 Test 7: breakindent + shift by +1 + nu + sbr=? briopt:sbr
  2     ab
?        m
?        x

 Test 8: breakindent + shift:1 + nu + sbr=# list briopt:sbr
  2 ^Iabcd
#      opq
#      BCD

 Test 9: breakindent + shift by +1 + 'nu' + sbr=# list
  2 ^Iabcd
       #op
       #AB

 Test 10: breakindent + shift by +1 + 'nu' + sbr=~ cpo+=n
  2     ab
~       mn
~       yz

 Test 11: strdisplaywidth when breakindent is on
strdisplaywidth: 46 == calculated: 64
Test 12: breakindent with wrapping Tab
d
w