import io
import os
from test.support import os_helper
DATA_TEMPLATE = ['line1=1']
DATA_CR = r'\n\r\t'.join(DATA_TEMPLATE) + '\r'
open_func = io.open
READMODE = 'r'
WRITEMODE = 'wb'
data = DATA_CR
if 'b' in WRITEMODE:
    data = data.encode('ascii')
with open_func(os_helper.TESTFN, WRITEMODE) as fp:
    fp.write(data)
with open_func(os_helper.TESTFN, READMODE) as fp:
    _ = fp.readline()
    pos = fp.tell()

python: ../Modules/_io/textio.c:2848: _io_TextIOWrapper_tell_impl: Assertion `skip_back <= PyBytes_GET_SIZE(next_input)' failed.
Aborted (core dumped)