Fix an out-of-bound index in pmerge() discovered by Zooko (SF bug 645404).  I'm not 100% sure this is the right fix, so I'll keep the bug report open for Samuele, but this fixes the index error and passes the test suite (and I can't see why it *shouldn't* be the right fix :-).
Fix an out-of-bound index in pmerge() discovered by Zooko (SF bug
645404).  I'm not 100% sure this is the right fix, so I'll keep the
bug report open for Samuele, but this fixes the index error and passes
the test suite (and I can't see why it *shouldn't* be the right fix
:-).

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator