is based on the line above, watch out for landing inside a triple
quoted string.  In this case, use iterative search +
parse-partial-sexp backwards to find the beginning of the string.

Note this does affect performance, but very little in the common cases
(I hope).  It could be made *much* faster by adding Emacs and XEmacs
dependent code -- different code naturally.  :-(

Fixes the following reported bug:

if len(sys.argv) >= 6:
    # More lines here
    fptr = open('/etc/hosts', 'w')
    fptr.write("""# /etc/hosts -- autocreated by /etc/ppp/ip-up
#
# Address from pppd
%-15s	%s

# For loopbacking
127.0.0.1	localhost

255.255.255.255	broadcast
""" % (ipaddr, ipname) )

os.chmod('/etc/hosts', 0644)