isomorphism() uses unnnormalized predicate strings

[goodmami]

Isomorphism still relies on unnormalized predicate strings. Compare the following where s1 and s2 only differ by the presence of _rel at the end of the predicates:

>>> from delphin.mrs import simplemrs, compare
>>> s1
'[ LTOP: h0 INDEX: e2 [ e SF: prop TENSE: past MOOD: indicative PROG: - PERF: - ] RELS: < [ proper_q<0:6> LBL: h4 ARG0: x3 [ x PERS: 3 NUM: sg IND: + ] RSTR: h5 BODY: h6 ]  [ named<0:6> LBL: h7 CARG: "Abrams" ARG0: x3 ]  [ _sleep_v_1<7:13> LBL: h1 ARG0: e2 ARG1: x3 ] > HCONS: < h0 qeq h1 h5 qeq h7 > ]'
>>> s2
'[ LTOP: h0 INDEX: e2 [ e SF: prop TENSE: past MOOD: indicative PROG: - PERF: - ] RELS: < [ proper_q_rel<0:6> LBL: h4 ARG0: x3 [ x PERS: 3 NUM: sg IND: + ] RSTR: h5 BODY: h6 ]  [ named_rel<0:6> LBL: h7 CARG: "Abrams" ARG0: x3 ]  [ _sleep_v_1_rel<7:13> LBL: h1 ARG0: e2 ARG1: x3 ] > HCONS: < h0 qeq h1 h5 qeq h7 > ]\n\n'
>>> x1 = simplemrs.loads_one(s1)
>>> x2 = simplemrs.loads_one(s2)
>>> x1 == x2  # generally a stricter test than isomorphism
True
>>> compare.isomorphic(x1,x2)
False
>>> compare.isomorphic(x1,x1)
True
>>> compare.isomorphic(x2,x2)
True

compare.isomorphic() should use pred.short_form() instead of pred.string