Problematic were files for which DOS-style EOLs were
detected (carriage return followed by newline, \r\n) but which had
some lines terminated solely by a newline (\n). In such a case the
EOL was only detected upon seeing the next \r\n, and the value
returned from the `getline()` function would return something that
everyone would judge to be multiple lines of text.
Fixes#2594.
