resolution by homogenization refuses multigraded rings, so towers fall back to resolution by syzygies

The following code gives an error. It is likely creating a new ring for homogenization, and incorrectly has that ring set to be a bigrading?

```
kk = QQ
A = kk[a,b,c,d]
B = A[x,y,z, Join=>false]
I = ideal(x-a-1, y-2, z-3)
res I
```

Note that the following works fine:

```
kk = QQ
A = kk[a,b,c,d]
B = A[x,y,z]
I = ideal(x-a-1, y-2, z-3)
res I
```