[BUG] Text.render() raises CanvasError for some non-UTF-8 encodings when 1 <= maxcols < 3

[AnonymouX47]

Description:

CanvasError is raised when ... (triple period) is used and 1 <= maxcols < 3 as in:

urwid.canvas.CanvasError: Canvas text is wider than the maxcol specified:
maxcol=2
widths=[3]
text=[b'...']
urwid target encoding=ascii

Introduced in #809.

Affected versions (if applicable)

• master branch (9fab329)
• Latest stable version from pypi
• Other (specify source)

Steps to reproduce (if applicable)

import urwid
urwid.set_encoding("ascii")
text = urwid.Text("Cool", wrap="ellipsis")
text.render((2,))

Expected outcome

The ellipsis should be truncated or replaced with blanks (spaces).

Might also want to include these edge cases in the tests.