I’m experiencing instability trying to use `quant`

to have redefinitions of sequences using `Pdefn`

happen at the proper timing:

First, evaluating the following plays two lines to demonstrate a 8-note line lining up with a 4-note line (such that the first note of the 8-note line always plays with the first note of the 4-note line):

```
(
TempoClock.tempo = 2;
Pdefn(\a,Pseq([3,2,2,2,2,2,2,2],inf));
Pdefn(\a).quant=8;
Pdefn(\b,Pseq([4,0,0,0],inf));
Pdefn(\b).quant=4;
Ppar([Pn(Pbind(\degree,Pdefn(\a),\octave,5),inf),
Pn(Pbind(\degree,Pdefn(\b),\octave,4),inf)]).play;
)
```

While that is playing, evaluating the following simply changes the 8-note line.

```
Pdefn(\a,Pseq([6,2,2,2,2,2,2,2],inf));
```

The expectation is that after redefinition, it would continue to line up with the 4-note sequence. Instead at times it transitions at a more or less random spot.

Any hints on how to lock this down?