globals() using For Loop against Generator

[cokofreedom at gmail.com]

if __name__ == '__main__':

    print "Globals (For Loop):"
    try:
        for i in globals():
            print "\t%s" % i
    except RuntimeError:
        print "Only some globals() printed\n"
    else:
        print "All globals() printed\n"

    print "Globals (Generator):"
    try:
        print "\n".join("\t%s" % i for i in globals())
    except RuntimeError:
        print "Only some globals() printed\n"
    else:
        print "All globals() printed\n"

>>>
>>> Globals (For Loop):
>>> 	__builtins__
>>> Only some globals() printed
>>>
>>> Globals (Generator):
>>> 	__builtins__
>>> 	__name__
>>> 	__file__
>>> 	i
>>> 	__doc__
>>> All globals() printed
>>>

Why is it with a generator I get everything out but with a for loop I
don't? I know that globals is not read-only but I would of expected
the same behaviour from both...

Any thoughts?