This simply uses difflib to compare the text without the offending
string to the full text.
Also ensures the summary line uses all space available. But the
terminal width is still hardcoded.
This stops difflib from printing many lines which had no change in
them anyway. It also avoids a bug in difflib which fails or hangs
when there are many trailing lines which are all identical.
--HG--
branch : trunk
This currently breaks the test_failuers.py example as that file counts
the number of failures in the demo. But this demo isn't fixed yet so
we'll leave it for now.
--HG--
branch : trunk