What prompted me to do these changes is that "Backward compatibility" 
section for 2.1 and earlier. How long are we going to keep this? According 
to svn, no commit has been made on the 2.1 branch since 2003. Is it safe 
to assume no unittest change is ever going to be backported to 2.1?

Then, while I was in it, I made other changes:

 - dict.has_key(key) --> key in dict
 - raise Exception, args --> raise Exception(args)
 - try..except KeyboardInterrupt: raise except: do_stuff() --> try..except 
Exception: do_stuff()
 - __metaclass__ = type --> all classes are now object subclasses

I'm not sure about the last one. Are those 2 equivalent? Is there a reason 
to keep is as "__metaclass__ = type"?

regrtest passed for me.

À propos modernizing unittest, may I suggest taking a look at #1034053. :)

Hi Virgil; thanks for stepping up to this.  Backward compatibility was 
largely for the sake of compatibility with Jython, which was always 
lagging far behind CPython.  I doubt it's a concern these days, and the 
unittest.py in the Python source repository should probably always be 
implemented in the nicest, cleanest way possible with the latest 
CPython.

Your changes look good to me, except for the KeyboardInterrupt one -- 
unless the way Ctrl-C is handled by Python has changed in the last 
couple of years, changing this "except:" clause will stop the text-mode 
test runner from being interruptible.  Admittedly the TextTestRunner 
should somehow be given an opportunity to detect Ctrl-C in order to stop 
when asked, but this diff does not allow for that.

Isn't it why KeyboardInterrupt is a subclass of BaseException instead of 
Exception (along with SystemExit)? so that "except Exception:" doesn't 
catch it?

Yes indeed - you're exactly right; just checked now.  Then disregard my 
previous comment!

All changes are looking fine to me but I haven't looked at the patch so far.

"__metaclass__ = type" is easier to write than subclassing from object.
Both are equivalent. 

>>> __metaclass__ = type
>>> class Foo: pass
...
>>> Foo
<class '__main__.Foo'>
>>> Foo.__bases__
(<type 'object'>,)
>>> type(Foo)
<type 'type'>

This patch has gone invalid due to some recent conflicting changes. I 
remade it and I'm resubmitting it hoping that it will get applied.

Will take a look.

Committed in r67985, thanks!