capfd.readouterr() converts \r to \n in pytest 6.0.0rc1 (regression)

[rowan-stein]

User request

• pytest 6.0.0rc1: capfd.readouterr() converts carriage return (\r) to newline (\n)
• Reported by Fedora package tests (e.g., borgbackup 1.1.13) failing due to CR preservation expectations

Observed failure

• When printing with end='\r', capfd.readouterr().out ends with '\n' instead of '\r'
• Regression bisected to commit 29e4cb5

Reproducer

def test_capfd_includes_carriage_return(capfd):
    print('Greetings from DOS', end='\r')
    out, err = capfd.readouterr()
    assert out.endswith('\r')

Expected

• capfd.readouterr() should preserve carriage returns (\r), not convert them to \n
  Notes
• Likely due to TextIOWrapper universal newline conversion introduced by the referenced commit.
• Implementation to follow in a PR to preserve CR by disabling universal newline translation in FD text capture.