(py-outdent-p): When looking at the previous line, watch out for

continuation lines.  This fixes this bug report, reported by Frank
Stajano.

# But if I split the "raise" line and reindent, the else WRONGLY goes up a
# level (?!?)

while condition1:
    if condition2:
        raise error3, \
              moreInfo4
else: # meant to close "if condition2"
    action5()